Estimation of Surface Area of Gold Nanoparticles Through the Adsorption Amount of Cysteine by Capillary Zone Electrophoresis


Microdialysis-integrated HPLC system with dual-electrode detection using track-etched membrane electrodes for in vivo monitoring of dopamine dynamics

A capillary high-performance liquid chromatography (HPLC) system equipped with a dual-electrode detector utilizing track-etched membrane electrodes (TEMEs) was combined with a microdialysis sampling setup. The electrochemical detector benefits from the high electrolysis efficiency of TEMEs, allowing for calibration-free coulometric detection and simplifying data analysis to determine the dopamine recovery through a dialysis probe. Additionally, this system was used for in vivo monitoring of dopamine in the right striatum of a mouse brain. Temporal changes in dopamine levels, including an exponential decay immediately after the dialysis probe insertion and an excess release of dopamine induced by a high concentration of potassium ions, confirmed the system's proper operation. Furthermore, subsequent measurements following the intraperitoneal injection of mirtazapine showed no increase in dopamine levels in the right dorsal striatum. The dual-electrode system displayed characteristic dopamine detection behavior, with anodic and cathodic peak pairs indicative of reversible electrochemical reactions. This capability facilitated the identification of the dopamine peak within the complex chromatogram of the mouse brain dialysate. The consistency between dopamine collection efficiency from standard solutions and dialysate indicated the absence of interfering electroactive substances overlapping with the dopamine peak in the chromatogram. This integrated analysis system successfully tracked temporal fluctuations in dopamine concentration within the mouse brain.

Journal of Chromatography. B, Analytical Technologies in the Biomedical and Life Sciences


Flow-through Potentiometric Residual Chlorine Sensor Using Activated Carbon Chamber Sandwiched Filter Electrode System

活性炭チャンバを挟持したフィルター電極システムを用いる 流通式電位差計測型残留塩素センサ


Capillary Electrophoretic Characterization of Platinum and Silver Nanoparticles in Aqueous Solution Prepared by a Solution Plasma Process


Conjugation monitoring of gold nanoparticles with alkanedithiols by capillary zone electrophoresis


Kinetic Analyses of Two-steps Enzymatic Oxidation from Hypoxanthine to Uric Acid with Xanthine Oxidase by Capillary Electrophoresis/Dynamic Frontal Analysis


Direct analysis of airborne microplastics collected on quartz filters by pyrolysis-gas chromatography/mass spectrometry

Journal of Analytical and Applied Pyrolysis


A flow-based enzyme-free biosensor fabricated using track-etched membrane electrodes: Selective and sensitive detection of uric acid


Simultaneous FIA determination of free and combined chlorine based on the difference in decomposition rate under UV light irradiation

紫外線照射下での光分解反応速度の違いに基づく遊離塩素と結合塩素のFIA同時定量


Detection behavior of phenolic compounds in a dual-electrode system assembled from track-etched membrane electrodes


Kinetic analyses of two-steps oxidation from L-tyrosine to L-dopaquinone with tyrosinase by capillary electrophoresis/dynamic frontal analysis

Tyrosinase catalyzes the oxidation of l-tyrosine in two stages to produce l-dopa and l-dopaquinone stepwise, and l-dopaquinone is subsequently converted to dopachrome. Most of the conventional analyses subjected only one-step reaction from l-tyrosine to l-dopa or from l-dopa to l-dopaquinone. In this study, kinetic analyses of two-steps oxidation of l-tyrosine with tyrosinase were made by capillary electrophoresis/dynamic frontal analysis (CE/DFA). When l-dopa was introduced into a capillary as a sample plug in a CE/DFA format, the enzymatic oxidation continuously occurred during the electrophoresis, and the product l-dopaquinone was subsequently converted to dopachrome which was detected as a plateau signal. A Michaelis-Menten constant of the second-step kinetic reaction, K, was determined as 0.45 ± 0.03 mmol L. In the analysis of the first-step kinetic reaction from l-tyrosine to l-dopa, l-dopa was not resolved by CE/DFA because both l-tyrosine and l-dopa are electrically neutral. The l-dopa formed and co-migrated at the l-tyrosine zone was calibrated beforehand with the final product of dopachrome detected as a plateau signal. Constantly formed l-dopa was successfully detected as a plateau signal of dopachrome, and a Michaelis-Menten constant of K was also determined as 0.061 ± 0.009 mmol L by the CE/DFA. CE/DFA is applicable to two-steps enzymatic reactions.

Analytical Biochemistry: Methods in the Biological Sciences


Highly stable gold nanoparticles in an aqueous solution without any stabilizer prepared by a solution plasma process evaluated through capillary zone electrophoresis


An Improved Reflection Colorimeter Integrated with a Coaxial Optical-fiber Cable for Highly Sensitive Solid-phase Colorimetry Using a Membrane Filter


Determination of Two-Steps Acid Dissociation Constants of L-Ascorbic Acid by Capillary Zone Electrophoresis


Kinetic analysis of the transphosphorylation with creatine kinase by pressure-assisted capillary electrophoresis/dynamic frontal analysis


Kinetic analysis of an enzymatic hydrolysis of p-nitrophenyl acetate with carboxylesterase by pressure-assisted capillary electrophoresis/dynamic frontal analysis


Kinetic analysis of substrate competition in enzymatic reactions with β-D-galactosidase by capillary electrophoresis / dynamic frontal analysis

Journal of Pharmaceutical and Biomedical Analysis


Capillary Electrophoretic Characterization of Water-Soluble Carbon Nanodots Formed from Glutamic Acid and Boric Acid under Microwave Irradiation


Determination of acid dissociation constants of flavin analogues by capillary zone electrophoresis

Acid dissociation constants (pK ) of nine kinds of flavin analogues as molecular catalyst candidates were determined by CZE. Although some of the analogues are instable and degradable under the light exposure or in alkaline aqueous solutions, the effective electrophoretic mobility of the flavin analogue of interest has been measured with the residual substance. The pK values of the flavin analogues were analyzed through the changes in the effective electrophoretic mobility with varying pH of the separation buffer. One or two steps pK values were determined by the analysis. One of the degraded species from the flavin analogues, lumichrome, was also detected in the CZE analysis, and its pK values were also determined. While coexisting impurities generated over the storage conditions were found in some analogues, the pK values of the target analogues were successfully determined with the help of the CZE separations. A pressure-assisted CZE was utilized for the determination or the estimation of the pK values of such analogues as possessing carboxylic acid moiety.


Capillary Electrophoresis/Dynamic Frontal Analysis for the Enzyme Assay of 4-Nitrophenyl Phosphate with Alkaline Phosphatase


Capillary Electrophoretic Characterization of Carbon Nanodots Prepared from Glutamic Acid in an Electric Furnace


Track-etched membrane-based dual-electrode coulometric detector for microbore/capillary high-performance liquid chromatography


Determination of Acid Dissociation Constants of Degradable Catecholamines by CZE

キャピラリーゾーン電気泳動法によるカテコールアミン類の酸解離定数の決定


Dispersion of Graphene in an Aqueous Solution with Poly(sodium 4-styrenesulfonate) Monitored by Capillary Electrophoresis


タンパク質結晶成長場及びX線回折実験用試料固定材としてのトラックエッチド メンブランフィルターの利用


Polyethylene Glycols for the Dispersion Development of Graphene in an Aqueous Surfactant Solution Studied by Affinity Capillary Electrophoresis


A Rapid Enrichment Technique for the Ultratrace Determination of Nickel in Water Samples Using a Nanofiber-composite Membrane Filter

A new method for the rapid enrichment and highly sensitive determination of nickel ion has been developed by using a nanofiber-composite membrane filter, which was fabricated by stacking a nanofibrous material made of nylon 6 over a water-permeable membrane filter. The noncharged nickel-α-furil dioxime complex was adsorbed on a nanofibrous layer of the membrane filter under significantly higher flow rates than those used for conventional solid-phase extraction techniques. Highly sensitive determinations with detection limits at sub-parts per billion levels were achieved by enrichment from 50 mL of the complex solution, and the enrichment was completed within 3 min. The color that was developed on the membrane filter was successfully subjected to visual colorimetric analysis and quantitative determination by solid-phase spectrophotometry. In addition, colorimetric determination was feasible with a handheld spectrometer after elution of the colored agent with 50 μL of acetone. This combination of rapid enrichment and spectrometric measurement in a small-volume sample provides a useful analytical method suitable for on-site analysis, which requires neither expensive instruments nor high laboratory skills.


Syntheses and properties of copper hydroxide nanosheets and controlled deposition

In this study, we synthesized copper hydroxide nanosheet and investigated its electro-chemical property and how to deposit it with a uniform amount. The precursor of the nanosheet was a layered copper hydroxide synthesized by the ion exchange of dodecyl-benzene sulfonate (DBS) with acetate in Cu2(OH)3(CH3COO)·H2O. The nanosheet was prepared by delamination of the layered copper hydroxide by dispersion in 1-butanol. Atomic force microscopy (AFM) images of the nanosheets showed lateral dimensions of ca. 2 μm with the height of ca. 4.5 nm. Cyclic voltammogram of the nanosheet in basic solution showed two cathodic peaks and two anodic peaks similar to the copper oxide electrode. To deposit the nanosheet, a quartz glass slide was dipped in the dispersion of the nanosheet in 1-butanol and dried after washing. This procedure was repeated and the ultraviolet (UV) and visible (Vis) light absorption spectrum of the slide was measured. The absorbance of the slide increased in direct proportion to the number of times of the dip-and-dry procedure. Thus, we confirmed that a controlled amount of nanosheet was deposited on the quartz glass.

International Journal of Modern Physics B


Effect of leaching conditions on the elution of metals from denitration catalyst wastes


Copper Speciation for Natural Water by On-site Sample Treatment/Solid-phase Extraction/Inductively Coupled Plasma Mass Spectrometry

Herein, we determined the contents of Cu(I), Cu(II), and hydrophobic Cu in natural water using on-site sample treatment, solid-phase extraction (SPE), and inductively coupled plasma mass spectrometry (ICP-MS) analysis. To prevent Cu species changes in the sampling, filtering and preconditioning steps were performed in a closed system using plastic syringes and a disposable membrane filter. Bathocuproin disulfonate (BCS) and ethylenediaminetetraacetic acid (EDTA) were selected as a Cu(I)-selective complexing agent and a Cu(II) masking agent, respectively, whereas ascorbic acid (AA) was used to reduce Cu(II) to Cu(I). Pre-conditioned samples were passed through a hydrophobic SPE column, and the retained Cu species were eluted with ethanol. Subsequently, the eluate was concentrated, and the residue was re-dissolved in 2 M HNO and subjected to ICP-MS analysis. No artificial changes of Cu(I) and Cu(II) species were observed at any time, with the analytical detection limit of total Cu and the blank value equaling 0.0008 and 0.0025 μg kg, respectively. The developed method was applied to real estuarine, riverine, and seawater samples collected in Tokushima prefecture, Japan.


Migration Behavior of Carbon Nanotube in Capillary Electrophoresis with Sodium Dodecyl Sulfate and Water-Soluble Nonionic Polymer


A Triple-Electrode Based Dual-Biosensor System Utilizing Track-Etched Microporous Membrane Electrodes for the Simultaneous Determination of L-Lactate and D-Glucose

Bulletin of the Chemical Society of Japan


Determination of Acid Dissociation Constants of Hydrochlorothiazide and Its Degradant through Measurement of the Effective Electrophoretic Mobilities in CZE

CZEによる電気泳動移動度測定に基づくヒドロクロロチアジドとその分解生成物の酸解離定数の決定


Solid-phase Visual Colorimetry for Trace As(III) Using a Nanofiber-composite Membrane Filter

ナノファイバー複合化メンブランフィルターを用いる微量ヒ素(III)の固相目視比色定量


Determination of the Acid-Base Dissociation Constant of Acid-Degradable Hexamethylenetetramine by Capillary Zone Electrophoresis

The acid-base equilibrium of hexamethylenetetramine (hexamine) was analyzed with its effective electrophoretic mobility by capillary zone electrophoresis. Although hexamine is degradable in a weakly acidic aqueous solution, and the degraded products of ammonia and formaldehyde can be formed, the effective electrophoretic mobility of hexamine was measured in the pH range between 2.8 and 6.9. An acid-base dissociation equilibrium of the protonated hexamine was analyzed based on the mobility change, and an acid dissociation constant of pKa = 4.93 ± 0.01 (mean ± standard error, ionic strength: 0.020 mol dm(-3)) was determined. The monoprotic acid-base equilibrium of hexamine was confirmed through comparisons of its electrophoretic mobility with the N-ethylquinolinium ion and with the monocationic N-ethyl derivative of hexamine, as well as a slope analysis of the dissociation equilibrium.


Analysis of Acid Dissociation Equilibrium of Bupropion by Capillary Zone Electrophoresis After the Heat-Degradation


Determination of Acid Dissociation Constant of Pravastatin under Degraded Conditions by Capillary Zone Electrophoresis

The acid dissociation constant of pravastatin was determined under degraded conditions. Pravastatin was degraded in an acidic solution (pH = 2.0) for 5 h, and the degradation solution was subjected to the measurement of the effective electrophoretic mobility by capillary zone electrophoresis. Although the amount of pravastatin decreased by the acid degradation, its acid dissociation constant was successfully determined with the residual pravastatin through its effective electrophoretic mobility. The determined acid dissociation constant value agreed well with the one obtained with freshly prepared solution and with some reported values.


Analysis of Chemical Equilibrium of Silicon-Substituted Fluorescein and Its Application to Develop a Scaffold for Red Fluorescent Probes

Fluorescein is a representative green fluorophore that has been widely used as a scaffold of practically useful green fluorescent probes. Here, we report synthesis and characterization of a silicon-substituted fluorescein, i.e., 2-COOH TokyoMagenta (2-COOH TM), which is a fluorescein analogue in which the O atom at the 10' position of the xanthene moiety of fluorescein is replaced with a Si atom. This fluorescein analogue forms a spirolactone ring via intramolecular nucleophilic attack of the carboxylic group in a pH-dependent manner. Consequently, 2-COOH TM exhibits characteristic large pH-dependent absorption and fluorescence spectral changes: (1) 2-COOH TM is colorless at acidic pH, whereas fluorescein retains observable absorption and fluorescence even at acidic pH, and the absorption maximum is also shifted; (2) the absorption spectral change occurs above pH 7.0 for 2-COOH TM and below pH 7.0 for fluorescein; (3) 2-COOH TM shows a much sharper pH response than fluorescein because of its pKa inversion, i.e., pKa1 > pKa2. These features are also different from those of a compound without the carboxylic group, 2-Me TokyoMagenta (2-Me TM). Analysis of the chemical equilibrium between pH 3.0 and 11.0 disclosed that 2-COOH TM favors the colorless and nonfluorescent lactone form, compared with fluorescein. Substitution of Cl atoms at the 4' and 5' positions of the xanthene moiety of 2-COOH TM to obtain 2-COOH DCTM shifted the equilibrium so that the new derivative exists predominantly in the strongly fluorescent open form at physiological pH (pH 7.4). To demonstrate the practical utility of 2-COOH DCTM as a novel scaffold for red fluorescent probes, we employed it to develop a probe for β-galactosidase.


The hydrophobic effect on electrodeposition of billirubin oxidase CotA


Leaching of metals from steel samples in peracetic acid


Equilibrium Analyses in Aqueous Solution under Accompanying Side Reactions by Capillary Zone Electrophoresis

キャピラリーゾーン電気泳動法を活用する副反応進行下での水溶液内平衡反応の解析

Analysis methods of equilibrium in an aqueous solution have been developed by capillary zone electrophoresis (CZE) utilizing its separation principle. The equilibrium of interest has been analyzed by affinity capillary electrophoresis (ACE) through the change in the electrophoretic mobility. Coexisting substances including degraded compounds are resolved from the equilibrium species by CZE, and an acid dissociation constant of photo-degradable haloperidol was determined in the presence of the degraded substances. In addition to the classical CZE separation, it has been noticed that gradually generated substances during CZE are resolved from the equilibrium species, and that the generated substances are observed as a leading/tailing signal to the equilibrium species. Slowly generated species from phenolphthalein by the addition of OH- in an alkaline pH solution was resolved from the equilibrium species, and the side reaction to the objective acid-base equilibria was excluded. Thus, two steps of the acid dissociation constants of phenolphthalein were determined by ACE. The acid-base equilibrium of tetrabromophenolphthalein ethyl ester (TBPE) was also analyzed by CZE under the degrading conditions, although the hydrolysis of the ester moiety accompanies with TBPE in acidic pH conditions. The precipitation reaction as a side reaction can also be excluded in the CZE analysis. The low concentration of analyte below its solubility is detected as a usual CZE signal, and the equilibrium of interest can be analyzed. The ion-association constants of dipicrylaminate ion with pairing cations were determined by ACE. Even under precipitating conditions, the precipitate is resolved from the equilibrium species by CZE, and it is dissolved again in the separation buffer. Acid dissociation constants of tetrabromophenolphthalein are determined by ACE under precipitable conditions. It was demonstrated in this study that the utilization of the CZE separation is advantageous on equilibrium analysis by ACE to such reactions as to be degradable and precipitable ones, compared to the ordinary analysis in homogeneous solutions, including potentiometric and photometric titrations.

キャピラリーゾーン電気泳動法(CZE)による均一水溶液中での平衡反応解析において，CZEの分離の特長を有効に活用する解析手法を開発した．解析の基本となるのはアフィニティキャピラリー電気泳動(ACE)の手法であり，測定対象物質の電気泳動移動度の測定を通して平衡物性を解析する．まず第一に，分離分析により共存物質，分解生成物がCZE分離される点を活用して，易分解性医薬品のハロペリドールの酸解離定数を決定した．さらに，CZE測定時間と同程度の分解反応速度を有する物質は測定中に平衡化学種から徐々に分離されてリーディング/テーリングシグナルとして観測されることに着目し，アルカリ性領域でOH-が付加する副反応を伴うフェノールフタレイン，酸性領域でエステル基の加水分解反応を伴うテトラブロモフェノールフタレインエチルエステルのそれぞれの酸解離定数をACEの手法により決定した．沈殿生成を副反応に伴う平衡反応の解析においては，難溶性物質の溶解度の問題に対して，溶解度までの低濃度ではCZEで通常のシグナルとして観測される特長に加えて，溶解度以上の濃度では生成した沈殿が平衡化学種から分離されて泳動液中で再溶解するために，CZE法では溶解度の問題はある程度許容される特長を見いだした．この特長を活用して，ジピクリルアミネートイオンの水溶液内イオン会合定数，テトラブロモフェノールフタレインの酸解離定数を決定することができた．分離分析法であるCZE法の利用は，一般的な平衡反応の解析手法である均一系における電位差滴定法，光度滴定法等と比較して，分離分析の手法，特長が平衡解析に有効であることを例示した．


Analysis of Binding Equilibrium of Phenylalkylamines to Brij 58 Micelle through the Measurement of Electrophoretic Mobility by CZE


Speciation of Chromium(VI) and Selenium(IV and VI) by High-Performance Liquid Chromatography-Fluorometric Detection Using 2,3-Diaminonaphthalene as a Single Derivatizing Reagent

A speciation method for chromate, selenite, and selenate was developed by high-performance liquid chromatography (HPLC)-fluorometric detection (FL) using a single derivatizing reagent. Chromium(VI) was determined based on the fluorescence intensity of 1H-naphtho[2,3-d][1,2,3]triazole (NAT) derived from 2,3-diaminonaphthalene (DAN) and nitrous ion; the NO2- was generated through a redox process between Cr(VI) and hydroxylamine hydrochloride (HACl). 4,5-Benzopiazselenol (Se-DAN) was also derived from Se(IV) and DAN, and it was resolved from NAT and detected by reversed-phase HPLC-FL operated under a single setting of an excitation and a fluorescence wavelength. Linear ranges of the calibration curve and detection limits were 0-20 µmol L-1 (correction coefficient: 0.995) and 0.1 µmol L-1 for Cr(VI), and 0-20 µmol L-1 (0.995) and 0.2 µmol L-1 for Se(IV), respectively. Concentration of Se(VI) was estimated from the difference in its concentration between total Se and Se(IV). The analytical procedure for the determination of total Se included a reduction of Se(VI) to Se(IV) with hydrochloric acid and potassium bromide. The linear range of the calibration curve and detection limit for Se(VI) was 0-20 µmol L-1 (correction coefficient: 0.990) and 0.3 µmol L-1, respectively. The proposed method was applied to the determinations of Cr(VI), Se(IV), and Se(VI) in a river water sample. Recoveries of Cr and Se species ranged between 98 and 104%, and the relative standard deviations were about 5% at 10 µmol L-1 levels of the species.

Bulletin of the Chemical Society of Japan


Facile synthesis of platinum nanoparticle-containing porous carbons and their application in amperometric glucose biosensing


Analysis of Ion-association Equilibrium of Precipitable Dipicrylaminate Ion in Aqueous Solution by Capillary Zone Electrophoresis

The ion-association equilibrium of the dipicrylaminate ion (DPA-) was investigated in an aqueous solution with alkali metal ions and with its 18-crown-6 ether complexes as pairing cations by capillary zone electrophoresis (CZE). Although DPA- is precipitable with the pairing cations of K+ and Cs+ in a homogenous aqueous solution, a low concentration of DPA- below its solubility suppressed the formation of the precipitates, and DPA- was detected as a usual CZE signal. Changes in the electrophoretic mobility of DPA- was analyzed for its ion-association equilibrium. The ion association constants determined were almost comparable among alkali metal ions, while the ion association constants were meaningfully large with a hydrophobic 18-crown-6 ether complex of K+. The CZE separation was also proved to be useful for the equilibrium analysis under precipitating conditions. It was suggested that the precipitable property of DPA- with K+ and Cs+ could not be attributed to the ion-association process in an aqueous solution, but to the condensation process concerning the intermolecular CH···O bond in the precipitate crystals, as reported.


Analysis of Acid Dissociation of Photo-degradable Haloperidol through the Measurement of Electrophoretic Mobility by Capillary Zone Electrophoresis

キャピラリーゾーン電気泳動法を用いる電気泳動移動度の測定による光分解性ハロペリドールの酸解離反応解析


Analysis of Fast and Slow Acid Dissociation Equilibria of 3',3'',5',5''-Tetrabromophenolphthalein and Determination of Its Equilibrium Constants by Capillary Zone Electrophoresis

Acid dissociation constants of 3',3'',5',5''-tetrabrompohenolphthalein (TBPP) were determined in an aqueous solution by capillary zone electrophoresis at an ionic strength of 0.01 mol/L. Two steps of the fast acid-dissociation equilibria including precipitable species of H2TBPP were analyzed at a weakly acidic pH region by using the change in effective electrophoretic mobility of TBPP with the pH of the separation buffer. On the other hand, an acid-dissociation reaction of TBPP at an alkaline pH region was reversible, but very slow to reach its equilibrium; the two TBPP species concerned with the equilibrium were detected as distinct signals in the electropherograms. After reaching its equilibrium, the acid-dissociation constant was determined with the signal height corresponding to its dianion form. Thus, three steps of the acid dissociation constants of TBPP were determined in an aqueous solution as pKa1 = 5.29 ± 0.06, pKa2 = 6.35 ± 0.02, and pKa3 = 11.03 ± 0.04.


Micellar Electrokinetic Chromatography of Graphene and Chemically Modified Graphenes with Dodecylbenzenesulfonate

Graphene and chemically modified graphenes were resolved by micellar electrokinetic chromatography (MEKC) using sodium dodecylbenzenesulfonate (SDBS) as a micelle matrix. Graphene was successfully dispersed in a micellar solution, and a consecutive and broad signal was obtained by the MEKC with a 20 mmol dm-³ aqueous SDBS solution for Graphene Nanoplatelets. Chemically oxidized graphene was less retained to the micelle than the Graphene Nanoplatelets by the proposed MEKC, and they were resolved with each other.


Determination of Ultra-Trace Amounts of Lead in River Water by Flow Injection Analysis Coupled with Computer-Controlled Auto-Pretreatment System Using Solid Phase Extraction Procedure


Determination of polyamines in Arabidopsis thaliana by capillary electrophoresis using salicylaldehyde-5-sulfonate as a derivatizing reagent


Determination of Acid Dissociation Constant of Degradable Tetrabromophenolphthalein Ethyl Ester by Capillary Zone Electrophoresis

An acid dissociation constant of tetrabromophenolphthalein ethyl ester (TBPE) was determined through the measurement of electrophoretic mobility by capillary zone electrophoresis (CZE). Although TBPE is degradable in acidic pH region and it gradually degraded at pH conditions around and below its pKa values in the time scale of the CZE measurement, equilibrium species of interest were detected as a peak-shaped signal with tailing of the degraded species. Changes in electrophoretic mobility of the equilibrium species of TBPE were analyzed at its detectable pH range in the presence of phenol red as a mobility standard. An acid dissociation constant of 3.47 ± 0.06 (pK(a), I = 0.01, 25°C, standard error) was determined for TBPE.


Fabrication and characterization of a thermostable quinoprotein aldose sugar dehydrogenase immobilized electrode

We fabricated a thermostable quinoprotein aldose sugar dehydrogenase (tPQQ-ASD derived from a hyperthermophilic archaeon Pyrobaculum aerophilum) immobilized electrode. The electrode was prepared by immobilizing agarose gel mixed with the enzyme and carbon nanofiber (CNF) on a carbon paste (CP) electrode containing p-benzoquinone (BQ) as an electron mediator. The electrocatalytic response was clearly observed by the addition of D-glucose at the electrode. The electrode properties such as pH, temperature dependency and substrate selectivity basically followed the enzyme properties. The current response against D-glucose increased with measurement temperatures up to 70°C, and response perturbation caused by dissolved oxygen level was not observed at the electrode. As for the results of long-term stability evaluation, the current response was stable for 30 days when the electrode was stored in HEPES buffer solution (pH 7.0) at 4°C.


Binding Analysis of 1-Alkyl-3-methylimidazolium Ions to Nonionic Surfactant Micelles by Capillary Zone Electrophoresis

キャピラリーゾーン電気泳動法による1-アルキル-3-メチルイミダゾリウムイオンの非イオン界面活性剤ミセルへの結合反応解析

The binding constants (KB) of four kinds of 1-alkyl-3-methylimidazolium ions to nonionic surfactant micelles have been determined through changes in the electrophoretic mobility in capillary zone electrophoresis. Larger binding constants were obtained with much bulky 1-alkyl-3-methylimidazolium ions. A linear free-energy relationship was observed with the KB values against the van der Waals volume of the cations. The KB values obtained with 1-alkyl-3-methylimidazolium ions are almost comparable with a series of N-alkylpyridinium ions previously reported. Both the binding constants and the linear free-energy relationship are smaller than the binding of anionic alkylbenzene sulfonate ions. The results have suggested a weak binding of cations to nonionic surfactant micelles.


Determination of Arsenic (III) by Sequential Injection/Anodic Stripping Voltammetry (SI/ASV) Using In-situ Thin Film-Modified Screen-Printed Carbon Electrode (SPCE)


Spectrophotometric Flow Injection Analysis of Chromium(VI) Coupled with On-line Solid-phase Extraction with Anion-exchange Resin Cartridge Column


Sensitive fluorimetric flow injection analysis for fluoride ion with a novel reagent, 2',7'-dichlorofluorescein di-tert-butyldimethylsilyl ether

A novel reagent, 2',7'-dichlorofluorescein di-tert-butyldimethylsilyl ether (FCl(2)TBS), was synthesized for fluoride ion and used for a sensitive fluorimetric flow injection analysis by detecting the recovery of fluorescence due to cleavage of Si-O bond. Four kinds of fluorescein di-tert-butyldimethylsilyl ether (FTBS) analogues were synthesized and FCl(2)TBS was the best. By introducing chlorine to FTBS, stability of the reagent, reactivity and the baseline signals were improved. The FIA system was three lines. The sample solution (aqua medium) was injected in the carrier solution (water) and merged with the reagent solution (2.0 × 10(-5)M FCl(2)TBS acetone solution), then mixed with phosphate buffer solution (pH 7.5). The fluorescence intensities were measured at (ex) 503 nm and (em) 527 nm. The calibration graph had linear relationship between (1.0-50.0) × 10(-6)M and the determinable limit was 1.0 × 10(-6)M. The relative standard deviation of 12 measurements with 1.0 × 10(-5)M F(-) solution was 1.0% and the sample throughput was 13 h(-1). The developed method was successfully applied to river and tap water samples.


Determination of Aluminum in Water Samples and Its Speciation Approach by Fluorophotometric Flow Injection Analysis with 8-Quinolinol Coupled with Micelle Sensitization


ルミノール化学発光を検出法とするシーケンシャルインジェクション分析における錯化剤および界面活性剤の増感効果

Some complexing agents and surfactants sensitize luminol chemiluminescence (CL) with Fe(III) or Fe(II) as a catalyst ; also the effect of the sensitizing reagents on the CL intensity was examined in sequential injection analysis (SIA). Solutions of luminol, H2O2 and a sample solution containing Fe(III) or Fe(II) were sequentially introduced into a holding coil, and the zones of the sucked solutions were immediately propelled to a CL detection cell ; the CL intensity was measured. In the case of the complexing agents as additives, tartrate and oxalate ions in the sample solution were most effective to improve the CL intensity. When surfactants were used as additives, the chemiluminescence was sensitized over the critical micelle concentrations of cationic cetyltrimethylammonium bromide and anionic sodium dodecylsulfate. Sensitization with the complexing agents and the surfactants in SIA are much more effective than in flow injection analysis. Since mixing of the sucked zones is not sufficient in SIA, the chemiluminescence would have been effectively sensitized.


キャピラリーゾーン電気泳動法による18-クラウン-6とフェニルアルキルアンモニウムの錯形成反応の解析

Complex formation equilibrium of phenylalkylammonium ions (PAA+) with 18-crown-6 (18C6) has been analyzed by capillary zone electrophoresis (CZE). The electrophoretic mobility of PAA+ (μep) was measured by CZE in the presence of 18C6 in a migrating buffer, and the μep values were used for equilibrium analysis. The μep values decreased with increasing concentrations of 18C6, and 1 : 1 complex formation constants, K, were determined. The K values for PAA+ in an aqueous solution are comparable to literature data reported for the ammonium ion. The K values increased with a longer alkyl chain in PAA+, except for the benzylammonium ion. The results suggested the contribution of hydrophobicity in PAA+, as well as CH/ϖ interactions for the benzylammonium ion. The K values also increased in mixed aqueous solvents with a decreased dielectric constant, which suggested the contribution of ion-dipole interaction in the complex formation reaction.


Weak Binding of N-Alkylpyridinium Ions to Nonionic Surfactant Micelles as Studied by Capillary Zone Electrophoresis

The binding equilibrium of N-alkylpyridinium ions to nonionic surfactant micelles was investigated through the changes in the electrophoretic mobility of the alkylpyridinium ions in capillary zone electrophoresis. The binding constants thus determined increased with increasing molecular volume of the alkylpyridinium ions. However, the binding constants are small compared with the ones for the anionic alkylbenzenesulfonate and polynitrophenolate ions at the same molecular volume.


Simple Kits of Colorimeter and Potentiometer for High School and Undergraduate Student Education

ものづくり教育を指向した簡易比色計及び電位差計キットの開発

Kits for an LED-base colorimeter and a potentiometer for ion-selective electrodes, dedicated to high school or undergraduate student experiments, have been developed. These kits are intended not only to provide experience chemical analysis, but also for manufacturing analytical instruments for themselves. A micro-controller was used to simplify the electronic circuit, to reduce costs, and to provide practical analytical performance to those kits. Both kits can be built within 2 hours and at expenses of less than 10 thousand yen. After the time and easiness for assembly and the analytical performance were evaluated with prototypes, print circuit boards for them were manufactured. These kits were used in lectures for high school students, high school teachers and undergraduate students. Almost all students were able to complete the kit within a given time, and could apply it to analytical experiments.

高校生あるいは大学生を対象として，分析機器の組立てを通じてものづくりを体験するとともに，完成した機器が実際の分析に応用できる性能を有するようなキットの開発を目的として，発光ダイオード(LED)を光源とする比色計と，イオン選択性電極と組み合せて使用できる電位差計を開発した．いずれも短時間(2時間以内)かつ安価(1万円以内)で製作できるよう回路を簡略化した．試作した装置を用いて組み立て性と分析性能を評価し，プリント基板を製作した．これらを実際に高校生，高校教員，及び大学生の実習に用いたところ，ほぼ全数が実習時間内に完成し，実用的な性能を有していることを確認できた．


Monitoring of Vitamin C Species in Aqueous Solution by Flow Injection Analysis Coupled with an On-line Separation with Reversed-phase Column

Two vitamin C species of ascorbic acid and dehydroascorbic acid in aqueous solution were monitored by flow injection analysis. Ascorbic acid and dehydroascorbic acid were resolved by a reversed-phase column, and dehydroascorbic acid was reduced to ascorbic acid by an on-line post-column reaction with dithiothreitol. Both natural and reduced ascorbic acids were photometrically detected at 260 nm, and the two vitamin C species were simultaneously determined. The determination range was from 0 to 8 x 10(-5)M with a limit of detection of 1.7 x 10(-6)M. The proposed method was applied to the conversion monitoring of ascorbic acid and dehydroascorbic acid in weakly acidic to weakly alkaline aqueous solutions, as well as to the determination of the vitamin C in some beverage samples.


Pre-evaluation of Metal Ions as a Catalyst on Chemiluminometric Sequential Injection Analysis with Luminol-H2O2 System

Catalytic effect of metal ions on luminol chemiluminescence (CL) was investigated by sequential injection analysis (SIA). The SIA system was set up with two solenoid micropumps, an eight-port selection valve, and a photosensor module with a fountain-type chemiluminescence cell. The SIA system was controlled and the CL signals were collected by a LabVIEW program. Aqueous solutions of luminol, H(2)O(2), and a sample solution containing metal ion were sequentially aspirated to the holding coil, and the zones were immediately propelled to the detection cell. After optimizing the parameters using 1 x 10(-5)M Fe(3+) solution, catalytic effect of some metal species was compared. Among 16 metal species examined, relatively strong CL responses were obtained with Fe(3+), Fe(2+), VO(2+), VO(3)(-), MnO(4)(-), Co(2+), and Cu(2+). The limits of detection by the present SIA system were comparable to FIA systems. Permanganate ion showed the highest CL sensitivity among the metal species examined; the calibration graph for MnO(4)(-) was linear at the concentration level of 10(-8)M and the limit of detection for MnO(4)(-) was 4.0 x 10(-10)M (S/N=3).


Adsorption Behavior of Uranium(VI) and Other Ionic Species on Cross-linked Chitosan Resins Modified with Chelating Moieties

Cross-linked chitosan resins with catechol (catechol-type chitosan, type 1 and type 2), iminodiacetic acid (IDA-type chitosan), iminodimetylphosphonic acid (IDP-type chitosan), phenylarsonic acid (phenylarsonic acid-type chitosan), or serine (serine-type chitosan) were prepared for the collection and concentration of uranium(VI). The adsorption behavior of U(VI) and other ionic species, such as metal ions and oxo-acid ions, on the cross-linked chitosan (base material) and chitosan resins modified with chelating moieties was examined using a column procedure. Especially, the catechol-type chitosan (type 2) adsorbed U(VI) at pH 2-7, and selectively collected U(VI) at acidic pH regions by forming a stable chelate with hydroxyl groups of catechol moiety introduced to the chitosan. Also, the adsorption properties of cationic and anionic species present in aquatic media were elucidated. The adsorption ability for U(VI) was in the order: catechol-type chitosan (type 2)>serine-type chitosan>phenylarsonic acid-type chitosan>the others. The catechol-type chitosan (type 2) was useful for the collection and concentration of uranium(VI).


Synthesis of novel chitosan resin possessing histidine moiety and its application to the determination of trace silver by ICP-AES coupled with triplet automated-pretreatment system

A novel chitosan resin, cross-linked chitosan functionalized with histidine moiety (histidine-type chitosan resin), was synthesized for the collection and concentration of trace silver in aquatic samples. A triplet automated-pretreatment system (Triplet Auto-Pret System) installed mini-columns packed with the synthesized histidine-type chitosan resin was coupled with an inductively coupled plasma-atomic emission spectrometry (ICP-AES) for a rapid and sensitive analysis. Adsorption behavior of 50 elements on the histidine-type chitosan resin was examined. A trace amount of Ag(I) was shown a good adsorption in wide pH regions (pH 5-9), and Ag(I) adsorbed was readily recovered with 1 M nitric acid solution. The limit of detection (3sigma) for silver was 0.03 microg L(-1). The system was successfully applied to river water and dipped water in silver coated container.


Sample Pretreatment Using Chitosan-based Chelating Resin for the Determination of Trace Metals in Seawater Samples by Inductively Coupled Plasma-Mass Spectrometry

A sample-pretreatment method using a chitosan-based chelating resin, ethylenediamine-N,N,N'-triacetate-type chitosan (EDTriA-type chitosan), was developed for the preconcentration of trace metals in seawater and separation of the seawater matrix prior to their determination by inductively coupled plasma-mass spectrometry (ICP-MS). The resin showed very good adsorption for transition metals and rare-earth elements without any interference from alkali and alkaline-earth metals in an acidic media. In the proposed method, an aliquot of a 50-mL sample at pH 4 was used. Metals adsorbed on the resin were eluted using 10 mL of 1 M nitric and measured by ICP-MS. The method was evaluated by the analysis of NASS-5 seawater reference materials for trace metals. Good agreement was obtained for most metals, which indicates that by the proposed pretreatment using the synthesized resin, seawater samples can be favorably measured by ICP-MS.


Synthesis of Chitosan-Based Resins Functionalized with Serine Moiety and Its Application to Determination of Trace Amounts of Uranium by FI/ICP-MS System


Adsorption Properties of Ionic Species on Cross-linked Chitosans Modified with Catechol and Salicylic Acid Moieties

Catechol-type chitosan resin and salicylic acid-type chitosan resin were easily synthesized for use in estimating the adsorption behavior of 34 elements at pH 1 - 7 in aquatic media. The catechol-type chitosan resin could adsorb Cu(II) at pH 3 - 7, In(III) at pH 4 - 6, Pb(II) and lanthanoids at pH 5 - 7, and U(VI) at pH 4 - 7 more effectively than the salicylic acid-type chitosan resin and the cross-linked chitosan resin (base material). Adsorption ability was in the order: catechol-type chitosan resin > salicylic acid-type chitosan resin > cross-linked chitosan resin.


Synthesis of Chitosan Resin Possessing a Phenylarsonic Acid Moiety for Collection/Concentration of Uranium and Its Determination by ICP-AES

A chitosan resin possessing a phenylarsonic acid moiety (phenylarsonic acid type chitosan resin) was developed for the collection and concentration of trace uranium prior to inductively coupled plasma (ICP) atomic emission spectrometry (AES) measurement. The adsorption behavior of 52 elements was systematically examined by packing it in a minicolumn and measuring the elements in the effluent by ICP mass spectrometry. The resin could adsorb several cationic species by a chelating mechanism, and several oxo acids, such as Ti(IV), V(V), Mo(VI), and W(VI), by an anion-exchange mechanism and/or a chelating mechanism. Especially, U(VI) could be adsorbed almost 100% over a wide pH region from pH 4 to 8. Uranium adsorbed was easily eluted with 1 M nitric acid (10 mL), and the 25-fold preconcentration of uranium was achieved by using a proposed column procedure, which could be applied to the determination of trace uranium in seawater by ICP-AES. The limit of detection was 0.1 ng mL(-1) for measurement by ICP-AES coupled with 25-fold column preconcentration.


Preconcentration and Decomposition of Perfluorinated Carboxylic Acids on an Activated Charcoal Cartridge with Sodium Biphenyl Reagent and Its Determination at µg L-1 Level on the Basis of Flow Injection-Fluorimetric Detection of Fluoride Ion

Perfluorinated surfactants of heptafluorobutylate and pentadecafluorooctanoate ions were adsorbed on an activated charcoal cartridge and decomposed with sodium biphenyl (SBP) reagent to form inorganic fluoride ion. The fluoride ion thus formed was determined by flow injection analysis (FIA) using quercetin-Zr complex as a fluorimetric reagent, where lambda(ex) and lambda(em) were 422 and 491 nm, respectively. The limit of detection for fluoride ion by the FIA system was developed to 1.1 x 10(-6)M (signal to noise ratio of three), when 50% (v/v) tetrahydrofuran (THF) was used as a dissolving solvent for quercetin. The perfluorinated surfactants in the sample solution were quantitatively adsorbed on the cartridge containing 100mg of activated charcoal and were decomposed with 0.5 mL of sodium biphenyl reagent after drying thoroughly by flowing through dry nitrogen gas. The fluoride ion formed was recovered with 3 mL of purified water as an eluent, and it was determined by the fluorimetric flow injection system. The blank fluorescence signal accompanied during the adsorption/decomposition on the cartridge was reduced by washing the activated charcoal with acetone. The blank signal was also observed from dimethoxyethane, which was used in sodium biphenyl reagent. When 600 mL sample solution was used and 200 times enrichment was applied, the heptafluorobutylate and pentadecafluorooctanoate ions at the concentrations of 2.1 microg L(-1) were quantitatively recovered as fluoride ion, and the limit of detections for the perfluorinated surfactants were 0.3 and 0.3 microgL(-1) for the two perfluorinated surfactants, respectively (3 sigma of the blank signal).


Adsorption Behavior of Cationic and Anionic Species on Chitosan Resins Possessing Amino Acid Moieties

Chitosan resins modified with amino acids, such as glycine, valine, leucine, and serine, were synthesized for investigating the adsorption behavior of cationic and anionic species, and showed good abilities for the adsorption of trace elements in aquatic media as follows: glycine for lanthanoids at pH 7, leucine for molybdenum at pH 1-5, serine for uranium at pH 2-7, and amino acids for bismuth at pH 1-7. Cationic and anionic species could be adsorbed by a chelating mechanism and an anion-exchange mechanism.


Flow-Injection Determination of Total Organic Fluorine with Off-line Defluorination Reaction on a Solid Sorbent Bed

Considering recent reports on widespread occurrence and concerns about perfluoroalkyl substances (PFAS) in environmental and biological systems, analysis of these compounds have gained much attention in recent years. Majority of analyte-specific methods are based on a LC/MS/MS or a GC/MS detection, however many environmental or biological studies would benefit from a total organic fluorine (TOF) determination. Presented work was aimed at developing a method for TOF determination. TOF is determined as an amount of inorganic fluoride obtained after defluorination reaction conducted off-line using sodium biphenyl reagent directly on the sorbent without elution of retained analytes. Recovered fluoride was analyzed using flow-injection system with either fluorimetric or potentiometric detection. The TOF method was tested using perfluorocarboxylic acids (PFCA), including perfluorooctanoic acid (PFOA), as model compounds. Considering low concentrations of PFAS in natural samples, solid-phase extraction as a preconcentration procedure was evaluated. Several carbon-based sorbents were tested, namely multi-wall carbon nanotubes, carbon nanofibres and activated carbon. Good sorption of all analytes was achieved and defluorination reaction was possible to carry out directly on a sorbent bed. Recoveries obtained for PFCAs, adsorbed on an activated carbon sorbent, and measured as TOF, were 99.5+/-1.7, 110+/-9.4, 95+/-26, 120+/-32, 110+/-12 for C4, C6, C8, C10 and C12-PFCA, respectively. Two flow systems that would enable the defluorination reaction and fluoride determination in a single system were designed and tested.


Sequential-Injection On-line Preconcentration Using Chitosan Resin Functionalized with 2-Amino-5-hydroxy Benzoic Acid for the Determination of Trace Elements in Environmental Water Samples by Inductively Coupled Plasma-Atomic Emission Spectrometry

A new chelating resin using chitosan as a base material was synthesized. Functional moiety of 2-amino-5-hydroxy benzoic acid (AHBA) was chemically bonded to the amino group of cross-linked chitosan (CCTS) through the arm of chloromethyloxirane (CCTS-AHBA resin). Several elements, such as Ag, Be, Cd, Co, Cu, Ni, Pb, U, V, and rare earth elements (REEs), could be adsorbed on the resin. To use the resin for on-line pretreatment, the resin was packed in a mini-column and installed into a sequential-injection/automated pretreatment system (Auto-Pret System) coupled with inductively coupled plasma-atomic emission spectrometry (ICP-AES). The sequential-injection/automated pretreatment system was a laboratory-assembled, and the program was written using Visual Basic software. This system can provide easy operation procedures, less reagent consumption, as well as less waste production. Experimental variables considered as effective factors in the improvement sensitivity, such as an eluent concentration, a sample and an eluent flow rate, pH of samples, and air-sandwiched eluent were carefully optimized. The proposed system provides excellent on-line collection efficiency, as well as high concentration factors of analytes in water samples, which results in highly sensitive detection of ultra-trace and trace analysis. Under the optimal conditions, the detection limits of 24 elements examined are in the range from ppt to sub-ppb levels. The proposed method was validated by using the standard reference material of a river water, SLRS-4, and the applicability was further demonstrated to the on-line collection/concentration of trace elements, such as Ag, Be, Cd, Co, Cu, Ni, Pb, U, V, and REEs in water samples.


Pseudo-Homogeneous Micelle Extraction of Ion-Associates Formed between Tetrabutylammonium Ion and Some Aromatic Sulfonate Ions into Nonionic Surfactant Micelle Studied through the Mobility Measurements in Capillary Zone Electrophoresis

Ion-association extraction of some aromatic sulfonate ions including alkylbenzene sulfonates with tetrabutylammonium ion (TBA+) into nonionic surfactant micelle has been investigated through the changes in the electrophoretic mobility. Nonionic surfactants of Brij 35 and Brij 58 were used as micelle substrates to which the ion-associates formed could distribute. The electrophoretic mobility of the aromatic sulfonate ions was measured by capillary zone electrophoresis in the presence of TBA+ and/or the nonionic surfactant to determine ion-association constants (K(ass)), binding constants of the anions to the nonionic surfactant micelle (K(B)), and binding constants of the ion-associates to the nonionic surfactant micelle (K(B,IA)). Nonlinear phenomena induced with the alkyl chain moiety were observed on K(ass) and K(B) by its linear structure and the mixed micelle formation, respectively. Larger K(B) values were obtained with Brij 58 as micelle matrix than with Brij 35, while the differences in K(B,IA) were small between Brij 58 and Brij 35.


Ion-Association Extraction of Nitrobenzoate Ions with Tetrabutylammonium Ion into Nonionic Surfactant Micelles as Studied by Capillary Zone Electrophoresis

Bulletin of the Chemical Society of Japan


Functionalization of Chitosan with 3,4-Dihydroxybenzoic Acid for the Adsorption/Collection of Uranium in Water Samples and Its Determination by Inductively Coupled Plasma-Mass Spectrometry

A chitosan resin derivatized with 3,4-dihydroxybenzoic acid moiety (CCTS-DHBA resin) was newly synthesized for the collection/concentration of trace uranium by using cross-linked chitosan (CCTS) as base material, and the adsorption behavior of uranium as well as 60 elements on the resin was examined by passing the sample solutions through a mini-column packed with the resin. After the elution of the collected elements on the resin with 1M HNO(3), the eluates were measured by inductively coupled plasma-mass spectrometry (ICP-MS). The CCTS-DHBA resin can adsorb several metal cations and several oxoanionic elements at appropriate pH. Among these metal ions, uranium shows an excellent adsorption behavior on this resin. Uranium as UO(2)(2+) species can be adsorbed on the resin by chelating mechanism with adsorption capacity of 330 mg g(-1) resin. Through the column treatment, the complete removal of large amounts of alkali and alkaline earth matrices without any loss of adsorption efficiency over prolonged usage were achieved with this resin. The CCTS-DHBA resin was applied to the adsorption/collection of uranium in tap water, river water and seawater samples with satisfactory results. The validation of the proposed method was carried out by analyzing uranium in the standard reference materials of SLRS-4, CASS-4, and NASS-5 after passing through the CCTS-DHBA resin, and the results showed good agreement with the certified values.


Ion-Association Extraction of Nitrophenolate Ions with Tetrabutylammonium Ion into Nonionic Surfactant Micelle

Ion-association extraction of some nitrophenolate ions with tetrabutylammonium ion (TBA(+)) into nonionic surfactant micelle has been investigated through the changes in the electrophoretic mobility. Nonionic surfactants of Brij 35 and Brij 58 were used as micelle substrates to which the ion-associates formed could distribute. The electrophoretic mobility of the phenolate ions was measured by capillary zone electrophoresis in the presence of TBA(+) and/or the nonionic surfactant. The electrophoretic mobility of the analyte anions decreased with increasing concentrations of the interacting reagent. Ion association constants (K(ass)) between TBA(+) and the phenolate ions, as well as binding constants of the anions to the nonionic surfactant micelle (K(B)), were determined through the mobility change by applying it to a non-linear least-squares analysis. Binding of the ion-associates was also observed from the aqueous phase to the micelle phase, when both TBA(+) and the nonionic surfactant are present. Binding constants of the ion-associates to the nonionic surfactant micelle (K(B,IA)), as well as micelle extraction constants of the ion-associates (K(ex,m)), were also determined by using the mobility change. The K(ex,m) values obtained were compared with the ion association-solvent extraction constants (K(ex,S)) between water and chloroform.


Novel Oxidation Reaction of Prochlorperazine with Bromate in the Presence of Synergistic Activators and Its Application to Trace Determination by Flow Injection/Spectrophotometric Method

A simple and fast flow injection spectrophotometric method for the determination of bromate in water samples was developed. The detection system is based on the oxidation of prochlorperazine (PCP) with bromate in strongly acidic medium. Large amounts of chloride and bromide was found, for the first time, to act as an activator, and to enhance the sensitivity for bromate detection. The oxidation product of PCP gives pink color, which can be used to monitor the reaction spectrophotometrically at 525 nm. Under the optimal conditions, the method is selective; only nitrite, chlorite and hypochlorite can interfere with the determination of bromate. The elimination of these three ions is discussed. The calibration graph for bromate determination was linear in the range of 10-130 microg L(-1) with a detection limit of 2.3 microg L(-1). The repeatability was satisfactory, with the relative standard deviation of 1.1% (25 microg L(-1), n=10). The sample throughput was 44 h(-1). The proposed method was found to be highly reliable for screening drinking waters containing bromate, which is above or below legislation limit of 10 microg L(-1).


誘導結合プラズマ発光分析のためのキレート樹脂を用いる高効率自動前処理濃縮

誘導結合プラズマ発光分析のためのキレート樹脂を用いる高効率自動前処理濃縮

An automatically controlled collection/concentration system for ICP-AES was developed. Elements were collected with small chelating disks and chelating resin with the iminodiacetate moiety packed in a line filter. This column was installed in a 6-way valve on the pretreatment system, which could be connected on line to ICP-AES. The flow rate was 1 ml min^<-1> and conditioning of the chelating disk was carried out by flowing 0.5 M ammonium acetate (pH 5.5) for 2 min, sampling for 5 min and washing for 1 min. Elution was done by passing through 2 M HNO_3 at 1.3 ml min^<-1> for 1 min. Bi, Cd, Co, Cr, Cu, Mn, Ni, Pb and V could be determined with 5.0 ml of the sample solution. The enrichment factors were 3∼15 times and the collection efficiencies were better than 80%. The detection limits (LOD) were from 0.003 for Mn to 0.311 for Bi, which were several 10 to 100-times lower than that of normal LOD of ICP-AES. This method was successfully applied to the determination of these metals in tap and river-water samples.

誘導結合プラズマ発光分析法(ICP-AES)のための自動捕集濃縮前処理法を開発した.元素の捕集濃縮にはイミノ二酢酸基をもつキレートディスクとキレート樹脂を用い,これらを市販のラインフィルターに詰め込んで捕集濃縮カラムを作製し,自動捕集濃縮装置のバルブに接続して用いた.自動輔集濃縮装置はコンピュータで制御可能であり,キレート樹脂のコンディショニングを2分間,元素捕集を5分間,洗浄を1分間,溶離を1分間で処理し,流量は1ml min^<-1>で行った.自動捕集濃縮装置はオンラインでICP-AESに接続した.試料溶液から各元素をpH5.5で捕集し,2M硝酸で溶離を行い,ビスマス,カドミウム,コバルト,クロム,銅,マンガン,ニッケル,鉛,バナジウムの9元素が同時定量可能であった.5mlの試料溶液を用いたときの濃縮倍率は3∼15倍程度であり,捕集率は低い場合でも約80%であった.検出下限は,最もよいマンガンで0.003ppb,最も悪いビスマスで0.31ppbであり,捕集濃縮をしない通常の測定に比べ数10∼100倍高感度となった.本法を水道水及び河川水中のこれらの微量元素の定量に応用したところ,良好な結果を得た.


コンピュータ制御されたフローインジェクション分析装置の開発と環境水中の硝酸イオン，亜硝酸イオン，アンモニウムイオン定量への応用

Flow injection analysis (FIA) systems with low power consumption and personal-computer control were developed by using solenoid pumps and an LED detector. Both programs for controlling the system and acquiring measurement data were written using LabVIEW. The FIA system was applied to the determination of nitrite ion in river-water samples based on diazotization and coupling reactions. Linear calibration graphs were obtained with the combination of pump(s) and photometric detector in the concentration range of nitrite ion at 0.5∼3.0×10^<-6> M. Nitrate and nitrite ions were also determined simultaneously by the system by using a Cd/Cu reduction column and a by-pass flow. Determination of ammonia in river-water samples was also realized by the system with a modified indophenol reaction.

低電力でパーソナルコンピュータによる制御が可能なフローインジェクション分析装置の開発を目的として,ソレノイドポンプと発光ダイオード(LED)検出器を用いるシステムを構築し,LabVIEWを用いて装置制御とデータ取り込みを行うプログラムを組み上げた.このフローインジェクションシステムを用いる分析法として,ジアゾ化カップリング反応に基づく河川水中の亜硝酸イオンの定量に適用した.各種ポンプと検出器の組み合わせにおいて,亜硝酸イオンの検量線は0.5∼3.0×10^<-6>M範囲で良好な直線性が得られた.また,Cd/Cu還元カラムを用いる亜硝酸イオンと硝酸イオンの分析ではバイパス流路への分岐と遅延により,両者を分別して定量することができた.インドフェノール法に基づく河川水中アンモニアの定量にも適用し,窒素分析を目的とする環境試料に適用可能であることを示した.


Chitosan as Cationic Polyelectrolyte for the Modification of Electroosmotic Flow and Its Utilization for the Separation of Inorganic Anions by Capillary Zone Electrophoresis

Cationic polyelectrolyte of chitosan was used for the reversal of electroosmotic flow in capillary zone electrophoresis. The chitosan was dissolved in acetic acid solution, and stable electroosmotic flow was obtained at the chitosan concentrations between 50 and 300 microg/mL. Separation of inorganic anions was carried out using the dynamically coated capillary by capillary zone electrophoresis. Nine kinds of anions were separated and detected with the capillary. The electrophoretic mobility of the analyte anions decreased with increasing concentrations of chitosan in the migrating solution through ion-ion interaction, but the migration order of the analyte anions was not changed in the concentration range of the chitosan examined. The signal shape for the analyte anions was developed by using field-enhanced sample stacking with 10 mM sodium sulfate.


Synthesis of Water-Soluble Phenylazosalicylaldehyde Analogues and Their Application to Capillary Electrophoretic Determination of Primary Amines

Several primary amines are known to be endogenous substances, and they are to be detected at very low concentration level. Novel water-soluble azo dyes as precolumn derivatizing reagents were synthesized for the analysis of primary amines with strong visible-light absorption by CZE. A coupling reaction was used to introduce a sulfophenylazo group to salicylaldehyde or 1-hydroxy-2-naphthaldehyde to extend the conjugation and to improve the solubility in water of the derivatizing reagents, as well as the target compounds of the reaction products with the primary amines. Two azo dyes of 5-(4-sulfophenylazo)salicylaldehyde sodium salt (AZO1) and 4-(4-sulfophenylazo)-1-hydroxy-2-naphthaldehyde sodium salt (AZO2) were synthesized. Separation of eight kinds of n-alkylamines was performed by CZE after the derivatization with AZO1 or AZO2. The addition of Brij 35 to the running electrolyte and to the sample solutions was necessary to improve the solubility and the resolution among the analytes. Both reagents, AZO1 and AZO2, were compared with each other in terms of the reaction time of derivatization, the detection sensitivity and the total analysis time. The derivatization process using AZO2 was applied to the determination of four biogenic amines, histamine, tyramine, cadaverine and putrescine, and LODs at around micromolar level were achieved for the four amines.


Determination of Bromate Ion in Drinking Water by Capillary Zone Electrophoresis with Direct Photometric Detection

Bromate ion in drinking water was determined by capillary zone electrophoresis (CZE) with direct photometric detection. Bromate ion in the sample solution was introduced and concentrated into the capillary by electrokinetic injection for 50s at -10 kV. Electrophoretic separation was made at an applied voltage of -25 kV and bromate ion was detected at wavelength 193 nm, at which the baseline was stabilized with less UV-absorbing acidic phosphate buffer. Bromate ion was detected within 5 min in the electropherogram. By increasing the electric conductivity in the migrating solution with 10 mM Na2SO4, a limit of detection (LOD) of 9 x 10(-10)M (0.1 microg/L BrO3-) was achieved. The proposed method was applied to the analysis of tap water and river water samples, but bromate ion was not detected. Because the practical samples contain relatively large amount of foreign ionic substances, the tap water sample was diluted to avoid the matrix ions. Bromate ion added in a tap water at the concentration of 8 x 10(-8)M was quantitatively recovered by diluting it 1/10.


Novel Catalytic Oxidative Coupling Reaction of N,N-Dimethyl-p-phenylenediamine with 1,3-Phenylenediamine and Its Applications to the Determination of Copper and Iron at Trace Levels by Flow Injection Technique

A new catalytic oxidative coupling reaction of N,N-dimethyl-p-phenylenediamine (DPD) with 1,3-phenylenediamine (mPD) in the presence of hydrogen peroxide has been developed for trace metals analysis. The rate of the oxidation/coupling reaction can be enhanced significantly by iron, copper and cobalt. These metal ions can catalyze the oxidation reaction of DPD to form an oxidized product; the oxidized DPD was then coupled with mPD to give a blue-colored product which was measured spectrophotometrically at 650 nm. On the basis of such a reaction scheme, two simple flow injection analysis methods for the determination of copper and iron have been developed. Detailed studies on chemical and FIA variables affecting the sensitivity of the detection were carried out. Interferences from several ionic species were examined for the determination of copper: the interference effect by Fe(III) and Fe(II) up to 1.5 mg L(-1) was successfully suppressed by pretreating sample with ammonium acetate buffer solution (pH 8.4). Good linearity of a standard calibration graph was obtained over the ranges of 0-8 and 0-2 microg L(-1) of copper and iron, respectively, and the detection limits were 0.05 and 0.02 microg L(-1) for copper and iron, respectively. The precision of the methods in terms of relative standard deviation were 1.4 and 1.5% of R.S.D. which were obtained from 10 injections of 2.0 and 1.0 microg L(-1) of standard copper and iron, respectively. The proposed methods were successfully applied to the determination of copper and iron in tap and river water samples. The accuracy of the proposed methods was assessed by the analysis of certified reference material of river water.


Simple and Highly Sensitive Spectrophotometric Flow Injection Method for the Determination of Iodate in Iodized Salt


Synthesis of a Chitosan-Based Chelating Resin and Its Application to the Selective Concentration and Ultratrace Determination of Silver in Environmental Water Samples


Kinetic-Spectrophotometric Method for the Determination of Trace Amounts of Bromide in Seawater

A novel simple, sensitive and rapid kinetic-spectrophotometric method is proposed for the determination of trace amounts of bromide. The method is based on its catalytic effect on the oxidation of methylene blue (MB) by hydrogen peroxide in strongly acidic solution. The oxidation reaction is activated by large amounts of chloride and can be monitored spectrophotometrically by measuring the decrease in the absorbance of MB at 746 nm. The determination of bromide is performed by a fixed-time method at the first 100 s from the initiation of the reaction. Unlike other kinetic-spectrophotometric methods for the determination of bromide, the proposed method does not require heating the solution. Bromide can be determined in the range from 80 to 960 microg l(-1) with the detection limit of 35 microg l(-1). The relative standard deviation of ten replicate determination of 480 microg l(-1) bromide was 1.4%. The influence of potential interfering ions was studied. The proposed method was satisfactorily applied to the determination of bromide in seawater without interfering effect from chloride ion.


Fabrication of C60 Field-Effect Transistors with Polyimide and Ba0.4Sr0.6Ti0.96O3 Gate Insulators

A flexible C_<60> field-effect transistor (FET) device has been fabricated with a polyimide gate insulator on the poly(ethylene terephthalate) substrate, and n-channel normally off FET properties are observed in this FET device. The field-effect mobility, μ, is estimated to be ~10^<-2> cm^2 V^<-1> s^<-1> at 300 K. Furthermore, the C_<60> FET has been fabricated with a high-dielectric Ba_<0.4>Sr_<0.6>Ti_<0.96>O_3(BST) gate insulator, showing n-channel properties; the μ value is estimated to be ~10^<-4> cm^2 V^<-1> s^<-1> at 300 K. The FET device operates at very low gate voltage, V_G, and low drain-source voltage, V_<DS>. Thus these C_<60> FET devices possess flexibility and low-voltage operation characteristic of polyimide and BST gate insulators, respectively.


Fabrication of a Logic Gate Circuit Based on Ambipolar Field-Effect Transistors with Thin Films of C60 and Pentacene


Ion-Association Analysis between Inorganic Anions and Symmetrical Tetraalkylammonium Ions in Aqueous-Acetonitrile Media by Capillary Zone Electrophoresis

Bulletin of the Chemical Society of Japan


Fabrication and Characterization of Field-Effect Transistor Device with C2v Isomer of Pr@C82

Endohedral metallofullerene field-effect transistor (FET) device was fabricated with thin films of C_<2v> isomer of Pr@C_<82>. This device showed n-channel normally-on type FET properties, where high bulk current of Pr@C_<82> was observed at gate voltage of 0 V. The mobility, μ, was estimated to be 1.5 x 10^<-4> cm^2 V^<-1> s^<-1> at 320 K, which is comparable to those of other endohedral metallofullerene FET devices. The normally-on properties have been found to originate from the high bulk current caused by the small energy gap of Pr@C_<82>.


A Chemiluminescence-Based Continuous Flow Aqueous Ozone Analyzer Using Photoactivated Chromotropic Acid

Ozone has become the oxidant of choice for water disinfection, especially in large water treatment facilities. This paper describes a fast and sensitive method for the determination of ozone content by reaction with photoactivated chromotropic acid (CA, 4,5-dihydroxynaphthalene-2,7-disulfonic acid), which results in intense chemiluminescence (CL). Freshly ozonated water from a recirculating ozonizer/reservoir is injected into a carrier stream of deionized water in the flow-injection mode. This flow mixes with a stream of photoactivated CA solution in a spiral cell placed directly on top of an inexpensive miniature (8mm diameter active area) photomultiplier tube (PMT). Alkaline CA is photoactivated by passing it through a FEP-Teflon((R)) coil (residence time approximately 50s) wrapped around a 1W UV lamp emitting at 254nm; without photoactivation, the signal is approximately 70-fold lower. The S/N=3 limit of detection for aqueous ozone is 3mugl(-1) and good response slope is obtained up to an ozone concentration of 1.4mgl(-1), the highest that could be made in this study. The response obeyed a quadratic equation with r(2)=0.9984. No interference from permanganate ion is observed. The proposed system was applied to the monitoring of ozonation status of a playa lake water that exhibited significant ozone demand.


Capillary Zone Electrophoretic Studies of Ion Association between Inorganic Anions and Tetraalkylammonium Ions in Aqueous-Dioxane Media

Ion association between inorganic anions and symmetrical tetraalkylammonium ions, R4N+ (R = Me, Et, Pr, n-Bu, n-Am, and 2-methyl butyl {isoamyl = iAm}) was investigated using ordinary silica capillary by capillary zone electrophoresis. An improved version of the Williams-Vigh method was used for the first time to measure the mobilities of the inorganic anions. Plots of log Kass against log dielectric constant in various media, revealed a smaller change in Kass compared to dielectric constant. These plots suggest that the Bjerrum's equation is inadequate in accounting for the associations of ions in a CZE setup.


シアニン系新規合成試薬を用いる陰イオン界面活性剤の定量

シアニン系新規合成試薬を用いる陰イオン界面活性剤の定量

For the spectrophotometric determination of anionic surfactants in aqueous media, cationic dyes with a 2,2'-thiacyanine skeleton were newly synthesized. Carbon numbers of 4 and 6 in the n-dialkyl chain combined at the N position of 2,2'-thiacyanine are new compounds. Fundamental information. such as the pK_a values, was obtained. These two compounds and purchased diethyl- and dipropyl-2,2'-thiacyanine were examined for the spectrophotometric determination of an anionic surfactant, DBS. Of these, 3,3'-dihexyl-2,2'-thiacyanine (DHT) showed the best sensitivity. The calibration graph for DBS with DHT was linear up to 1×10^<-5> M, and the detection limit was 4×10^<-7>M. By a hydrophobic interaction, even a cationic surfactant, Zephiramine, and a nonionic surfactant, Triton X-100, could react with DHT. The ion-association constants for these surfactants with DHT were obtained.

水溶液一相系でイオン会合反応を利用する陰イオン界面活性剤直接定量のための陽イオン性染料を新規に合成した.基本骨格はシアニンとし,二つのNに炭素数の異なるn-アルキル鎖を導入した四級塩染料を合成した.アルキル鎖の炭素数4と6のものは新規合成化合物であり,pK_aを求めた.炭素数2と3の市販品と合成した陽イオン試薬を用い,吸光光度法により陰イオン界面活性剤(DBS)との最適反応条件を検討した.3,3'-ジヘキシル-2,2'-チアシアニン(DHT,C6の試薬)を用いて,10^<-6>MオーダーのDBSを定量することができ,検出下限は4×10^<-7>Mであった.また,疎水性相互作用により,非イオン性界面活性剤,陽イオン界面活性剤とも反応することが分かり,DHTとのイオン会合定数を求めた.


An Investigation of Weak Ion Association Equilibria between Inorganic Anions and Tetraalkylammonium Ions in Ethanol-Aqueous Media Using Capillary Zone Electrophoresis


水溶性シッフ塩基へのマージングゾーン誘導体化/逆相分配高速液体クロマトグラフィーによるn-アルキルアミン類の分離定量

Separation and determination of w-alkylamines were investigated with anionic aldehydes to form water-soluble Schiff bases by using reversed-phase high-performance liquid chromatography (RP-HPLC). Two labeling reagents of salicylaldehyde-5-sulfonate (SAS) and 4-(4-sulfophenylazo)-1-hydroxy-2-naphthaldehyde (SPAHNA) were investigated. Sample solution containing the analytes and reagent solution were simultaneously injected and merged in the flow line, and water-soluble Schiff bases were formed in the reaction tube with its length of 5 m and at 70℃. The Schiff bases were resolved with water-methanol eluent on a reversed-phase column and photometrically detected. The entire analysis time including on-line derivatization, column separation and detection was accomplished within 25 min with SAS and 18 min with SPAHNA. The determination range for the n-alkylamines are 0∼50 μM with the limit of detections at 0.5∼1.0 μM for SAS and 0.08∼0.20 μM for SPAHNA.

_<n->アルキルアミン類の分離定量法として,陰イオン性アルデヒドを誘導体化試薬として用いる吸光検出-逆相分配高速液体クロマトグラフイーを検討した.誘導体化試薬としては,サリチルアルデヒド-5-スルホン酸イオン(SAS)と4-(4-スルホフェニルアゾ)-1-ヒドロキシ-2-ナフトアルデヒド(SPAHNA)を用いた._<n->アルキルアミンを含む試料溶液と試薬溶液はそれぞれの流路に同時に注入され,マージングゾーン法によりオンラインで混合され,5m,70℃の反応コイル中で水溶性シッフ塩基へと誘導体化された.生成した水溶性シッフ塩基は逆相カラムにより分離され,吸光検出された.オンライン誘導体化とカラム分離/検出を含む分析時間は,SASを用いた場合25分,SPAHNAを用いた場合は18分であった.アルキルアミン類に対する検量線は0∼50μMの範囲で良好な直線性が得られ,検出限界は,SASを用いた場合0.5∼1.0μM,SPAHNAを用いた場合は0.08∼0.20μMであった.


微量フロー滴定分析法の開発と酸塩基滴定への応用

微量フロー滴定分析法の開発と酸塩基滴定への応用

A now titration analysis method based on flow ratiometry was developed in this study from the viewpoint of simplicity, rapidity, automation, and cost efficiency. Sample and titrant solutions react while the solutions are continuously propelled by individual pumps at different flow rates. The flow rates are accurately controlled and changed independently, and the color change of an indicator gives an equivalent point. The concentration of analyte was determined by using the ratio of the flow rate and the equivalent point. The fundamental properties of the flow titration method were evaluated through acid-base titration, and compared with the conventional manual titration. When Phenolphthalein or Cresol Red was used as an indicator added in either the sample solution or the titrant solution, linear calibration graphs were obtained for all titrations examined, including strong and weak acids. The proposed method was applied to the titration of carbonate salt using Bromocresol Green and Phenolphthalein. Two isolated end-points were obtained in one sequential measurement corresponding to carbonate and bicarbonate ions. The proposed titration method was applied to the analysis of commercial vinegar samples. The results agreed well with the ones obtained by the conventional titration method; the relative standard deviations for the end point were within 0.3%. The volume of wastewater per one measurement can be reduced down to about 100 μl by the proposed method, while a practical method requires about 50 ml.

容量分析法の簡便化,迅速化,自動化及び省力化を含む高機能化を目的として,送液ポンプの流量比に基づくフロー滴定システムの構築と応用について検討した.フロー滴定分析法は,連続して流れる試料液,滴定剤溶液の正確な流量制御を基本原理としている.2台の送液ポンプを用いてそれらの流量を変化させながら試料液(被滴定液)と滴定剤(滴定液)を送液し,流れ内において混合・反応させ,指示薬の変色を用いて試料液中の分析対象物質濃度を流量比から定量する容量分析法である.各種酸塩基滴定を通して本法の性能評価を行い,従来法との比較を行った.酸塩基指示薬としてフェノールフタレイン,あるいはクレゾールレッドを試料液又は滴定剤へ添加したところ,強酸,弱酸を問わず検討したすべての系において直線性の高い検量線が得られた.また,終点検出の相対標準偏差は0.3%未満であった.更に,滴定剤に2種類の指示薬を用いる多塩基酸・多酸塩基の連続滴定法について検討した.炭酸塩の分析ではブロモクレゾールグリーンとフェノールフタレインを指示薬として用い,炭酸イオン,重炭酸イオンに由来する二つの当量点を一試料測定で検出できた.本法を市販されている食酢の分析に適用したところ,従来法により決定した酢酸濃度と良好な一致を得た.1試料測定当たりの廃液量は50 ml程度から100μl程度まで大幅に低減化することができ,ブロー滴定分析法により全操作の自動化,試料・廃液量の大幅な低減化,滴定時間の短縮等の高機能化を達成した.


Evaluation of Weak Ion Association between Tetraalkylammonium Ions and Inorganic Anions in Aqueous Solutions by Capillary Zone Electrophoresis

The evaluation of weak ion association between eleven (11) inorganic anions (charge -1 to -3) and five n-tetraalkylammonium ions, R4N+ (R: methyl, Me; ethyl, Et; propyl, Pr; butyl, Bu; pentyl, Am) in aqueous media at 25 degrees C was studied. The analysis of ion association equilibria was carried out under acidic condition (formate buffer, pH 3.5) at low separating potential (-10 kV) using a coated capillary with suppressed electroosmotic flow (micro = 4 x 10(-5) cm2 V(-1) s(-1)). Direct UV detection was done at anode (lambda = 220 nm). The combination of the aforementioned conditions ensured that ion association constants, Kass, between n-tetraalkylammonium ion and the small inorganic anions were reliably determined after a non-linear least squares (NLLS) treatment of the measured anion's mobility. Like their larger counterparts, small anions showed increased interaction with an increase in size of pairing ions. Moreover, for a specific cation, the interaction of small anions increased with an increase in size of the hydrated anions as reflected by the relationship between the Kass and the Stokes' radius. A favourable comparison exists between the results presented in this work and those previously documented from other analytical techniques like conductometry. Qualitatively, the mobility of the anions appeared to obey the Hückel's model more closely than the more elaborate Zwanzig and Hubbard-Onsager models.


Chemiluminometric Measurement of Atmospheric Ozone with Photoactivated Chromotropic Acid

A highly sensitive, robust, fast, affordable measurement system based on interfacial gas-liquid chemiluminescence (CL) on a wetted transparent screen directly on top of a miniature photomultiplier tube provides the basis of an attractive method for ozone (O(3)). Alkaline chromotropic acid (CA, 4,5-dihydroxynaphthalene-2,7-disulfonic acid) chemiluminesces upon exposure to ozone. No light emission is observed from exposure of alkaline CA to NO(2) or H(2)O(2). However, response to ozone is highly dependent on the age and storage condition of the CA solution. As such, quantitative analysis will require frequent calibration, and the method will not be attractive. We have discovered that photoactivation plays the key role in producing (a) compound(s) from chromotropic acid that appear(s) to be the primary agent(s) responsible for the CL reaction with O(3). We thus devised a method wherein a flowing solution of CA (that is stable in neutral/acidic solutions) is rendered alkaline and then exposed for a few seconds on-line to UV radiation. The solution then reacts with ozone on a screen consisting of an "invisible" nylon stocking that provides for low liquid residence time and high light throughput and results in an LOD of 40 pptv, a determination range at least up to 230 ppbv, and 10-90% and 90-10% response times of 130 and 80 ms, respectively. Intra- and interday repeatabilities at the same concentration were 0.32 and 3.8% in relative standard deviation. On the basis of aging, CL, chromatography, and chromatography-mass spectrometry studies, we suggest that the primary CL-active species are likely dimeric semiquinone species derived from CA by a series of radical reactions.


Investigation of Salicylaldehyde-5-Sulfonate as a Precolumn Derivatizing Agent for the Determination of n-Alkane Diamines, Lysine, Diaminopimelic Acid, and Isoniazid by Capillary Zone Electrophoresis

Reactions of primary amines with salicylaldehyde-5-sulfonate (SAS) lead to the formation of stable Schiff bases at weakly alkaline pH and at moderate temperature in an ethanol-rich aqueous solution. Some alkane diamines were converted to salicylaldimine with SAS, and the products were resolved and detected by capillary zone electrophoresis (CZE). The reactivity of SAS was applied also to the derivatization of amino acids. Optimal conditions for the analysis of lysine in the presence of diaminopimelic acid, the metabolite of lysine, were investigated. Addition of Na(2)SO(4) into the migrating solution enhanced the stacking effect, and led to increase in the detection limits. Another advantage of the use of SAS is its ability to form stable water-soluble metal chelate as Schiff base ligands. For practical analysis, the copper chelate of the Schiff base of isoniazid, which is known as the most active antibacterial used in the treatment of pulmonary tuberculoses, was investigated, and the detection limit of isoniazid was improved in the magnitude of 11 times compared with the one of free isoniazid.

Journal of Pharmaceutical and Biomedical Analysis


2-(5-ニトロ-2-ピリジルアゾ)-5-(N-プロピル-N-スルホプロピルアミノ)フェノールを用いるキャピラリー電気泳動法によるニッケル，鉄塩中の極微量不純物の定量

2-(5-Nitro-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino) phenol (Nitro-PAPS) was used for a quantitative determination of ultratrace-level metal ions in commercially available metal salts by capillary zone electrophoresis. At pH 7, Nitro-PAPS reacts with various metal ions to form chelate compounds having large molar absorptivities. Although chelate formation is useful for the highly sensitive detection of metal ions, the resolution of the metal complexes is poor at pH 7. Cetyltrimethylammonium bromide was added to suppress any electroosmotic flow. The hydration of nitro groups of a chelating agent and chelates was controlled by the addition of urea. Sodium sulfate was also utilized to sharpen the signals of metal chelates by a field-enhanced stacking effect. As a result, the resolution was improved and the determination of 10^-7 M level metal ions was possible. The proposed method was applied to the analysis of metal impurity at ultratrace levels in commercially available nickel and iron salts.

市販金属塩中の極微量金属不純物の定量法として,2-(5-ニトロ-2-ピリジルアゾ)-5-(N-プロピル-N-スルホプロピルアミノ)フェノール (Nitro-PAPS) とのキレートを分離,検出するキャピラリー電気泳動法について検討した.各種金属イオンと定量的に反応する pH7 の条件では,高感度検出が可能であるが,多くの金属錯体の分離は十分でない.そこで,電気浸透流やキレートの電気泳動移動度を変化させる効果のある第四級アンモニウム塩等の添加を検討し,種々な相互作用試薬を用いて分離の改善を図った.その結果,臭化セチルトリメチルアンモニウムの添加で電気浸透流が抑制され,硫酸ナトリウムの添加によるスタッキング効果の活用によりシグナルが鋭敏化され,尿素の添加でニトロ基周りの水和を抑制したところ,金属キレートの分離性能が向上した.本法により 10^-7 M レベルの Fe, Co, Ni, Cu の分離定量が可能になり,市販特級金属塩中の極微量金属の分析に適用したところ,ppm (=10^-6 g/g) レベルの金属不純物を定量することができた.


1,8-ジアミノナフタレン-3,6-ジスルホン酸骨格を持つ新規水溶性蛍光試薬の合成と銅イオンの高感度定量への応用

Water-soluble fluorescent reagents, 1,8-di-(toluene-4-sulfonylamino)-naphthalene-3,6-disulfonic acid (BTND) and 1,8-di-(trifluoromethanesulfonylamino)-naphthalene-3,6-disulfonic acid (BTFND), were newly synthesized. The reactivities of these fluorescent reagents to Cu^2+, Ni^2+, Co^2+, Cd^2+, Pb^2+, V^V, Ag^+, Fe^3+, and Mg^2+ were examined. BTFND was reacted with 8 metal ions, except for Pb^2+, to show fluorescence quenching. BTND was selective to Cu^2+, and the fluorescence was quenched quantitatively at pH 7 in an aqueous solution (λ_ex=360 nm and λ_em=405 nm). The calibration graphy for Cu^2+ with BTND was rectilinear over the concentration range from 0 to 10^-5 M and the detection limit was 2.0×10^-7 M. BTND has many advantages, such as selectivity for Cu^2+, high sensitivity, and a simple procedure.

水溶性蛍光試薬として 1,8-ジヒドロキシナフタレン-3,6-ジスルホン酸(クロモトロープ酸)に類似した1,8-ジアミノナフタレン-3,6-ジスルホン酸骨格を持つ1,8-ジ-(トルエン-4-スルホニルアミノ)-ナフタレン-3,6-ジスルホン酸 (BTND) 及び1,8-ジ-(トリフルオロメタンスルホニルアミノ)-ナフタレン-3,6-ジスルホン酸 (BTFND) を合成し,金属イオンとの反応性を検討した.BTFND は検討した8種類の金属イオンと反応し消蛍光を示した.また BTND は銅(II) イオンと選択的に反応することが分かった.BTND は水溶液中 pH7 で銅(II) イオンと定量的に反応し,消蛍光を示したので,検量線を作成したところ,銅濃度0∼10^-6Mの範囲で直線関係を示した (λ_ex=360 nm, λ_em=405 nm).本法の銅(II) イオンの検出下限は 2.0×10^-7M であった.BTND は水溶液中で反応し,定量操作が簡便で,銅(II) イオンに対する高感度・高選択的な蛍光試薬であることが分かった.


Equilibrium Analysis of Reactions of Metal-Pyridylazoresorcinolato Chelates with Quaternary Ammonium Ion, Nonionic Surfactant and Polyethylene Glycol in Aqueous Solution by Capillary Zone Electrophoresis

The resolutions of metal-4-(2-pyridylazo)resorcinol chelates by capillary zone electrophoresis (CZE) were investigated in the presence of some interacting reagents; also, equilibrium reactions between the chelates and the interacting reagents were analyzed in an aqueous solution. Among nine metal chelates formed in aqueous solution, the chelates of VV, FeII, CoIII, NiII, and CuII were resolved and detected by CZE, while other chelates were decomposed during electrophoretic migration. The electrophoretic mobility of the chelates of FeII, NiII, and CuII increased with increasing pH of the migrating solution; also, the acid-dissociation constants of these three chelates were determined by analyzing the mobility change. The ion-association constants of the five anionic chelates and pyridylazoresorcinolate ion with quaternary ammonium ions were also determined by analyzing the mobility change. The binding behavior of the ligand and its chelates with nonionic surfactant micelle, as well as with polyethylene glycol, were investigated, and their binding constants were determined through the mobility change. When Brij 35 was used as a nonionic surfactant interacting with the anionic chelates, the FeII chelate decomposed at Brij 35 concentrations over 6.67 mM. The equilibrium constants and the reactivity were compared with each other.


Continuous In-Situ Analysis of Total Carbonate in Water by a Reversed-Flow Injection Method


Complex Formation Analysis of Water-Soluble Calixarenes by Capillary Zone Electrophoresis

The equilibria of complex formation reactions between various kinds of cations and anionic calixarenes in an aqueous solution were analyzed by capillary zone electrophoresis on the basis of the change in electrophoretic mobility of the calixarenes. The apparent electrophoretic mobility of the calixarenes decreased with increasing concentrations of alkali metal ions and quaternary ammonium ions. Equilibrium constants were determined by a non-liner least-squares analysis using the changes in apparent electrophoretic mobility. The complex formation constants obtained with alkali metal ions were in the order of 10(2.3) - 10(3.0), and those with quaternary ammonium ions were 10(2.9) - 10(4.2), providing less selectivity among them. The selectivity of the calixarene toward alkali metal and quaternary ammonium ions in aqueous solution involves flexible structure, and compensative interactions of electrostatic and hydrophobic interactions. From the results obtained in this work, the electrophoretic method has proved to be useful for analyzing the reactivity of anionic calixarene in aqueous solution.


Separation and Determination of n-Alkylamines and Histamine by Capillary Zone Electrophoresis Using Salicylaldehyde-5-Sulfonate as a Derivatizing Reagent

Sodium salicylaldehyde-5-sulfonate (SAS) was investigated as a derivatizing reagent for the separation and determination of primary amines by capillary zone electrophoresis (CZE). The amines were derivatized with SAS to the corresponding Schiff bases before their determination. Optimal conditions for the formation reactions of the Schiff bases and the CZE analysis were investigated in details. The Schiff bases were formed almost completely within 9 min in 40%(v/v) ethanol solution at 40 degrrees C. A migrating solution containing 40%(v/v) ethanol and 20 mM phosphate buffer (pH 7.8) was found to be preferable for the stability of the Schiff bases. Eight kinds of n-alkylamines were derivatized with SAS under the optimal conditions and the derivatives were successfully separated by a CZE analysis. The proposed method allows simultaneous, sensitive and sufficiently precise determination of the n-alkylamines with the alkyl chain length from 3 to 12 of methylene groups. The derivatization process with SAS was successfully applied to the detection of histamine at a very low level. The detection limit was 2.5-10(-6) M, and it was improved in the order of 8 times compared with the CZE analysis without derivatization.


Binding of Phenol Derivatives to Nonionic Surfactant Micelles as Studied by Capillary Zone Electrophoresis

Bulletin of the Chemical Society of Japan


Highly Sensitive Determination Method for Total Carbonate in Water Samples by Flow Injection Analysis Coupled with Gas-Diffusion Separation

A spectrophotometric method for the determination of total carbonate in water samples was developed. The method is based on the color change of an acid-base indicator in relation to the concentration of permeable gas substances through a membrane. By using a new portable FIA system equipped with a gas-diffusion unit, a highly sensitive and on-site determination of total carbonate in aqueous solutions was investigated. A new color-change system with 4-(2',4'-dinitrophenylazo)-1-naphthol-5-sulfonic acid (DNN5S) was developed. Absorbance changes of the reagent solution were measured at 450 nm with a light-emitting diode (LED) as a light source. A new type of gas-diffusion unit was used, and was constructed with double tubing: the inner tubing was a micro porous PTFE (polytetrafluoroethylene) tubing (1.0 mm inner diameter and 1.8 mm outer diameter, pore size 2 microns, porosity 50%); the outer tubing was made of glass with 2.0 mm inner diameter. The optimized system conditions were as follows: the sample size was 200 microliters, the temperature of the air bath for the gas-diffusion unit was 25 degrees C, and the length of the gas-diffusion unit was 15 cm; each flow rate was 0.3 ml min-1. For measuring carbonate at low concentrations, a method for preparing water with less carbonate was proposed: the carbonate content of the water was decreased down to 5 x 10(-7) M. The calibration graph was rectilinear from 1 x 10(-6) M to 10(-3) M, and the detection limit (corresponding to a signal-to-noise ratio of 3) was 1 x 10(-6) M of carbonate. The relative standard deviation (RSD) of ten measurements of 2.3 x 10(-5) M Na2CO3 solution was 1.9%. The total carbonate in various kinds of water (such as river, sea, rain, distilled and ultra purified) was determined.


Analysis of Complex Formation between Crown Ethers and Potassium Ion by Determining Retention Factors in Reversed-Phase High-Performance Liquid Chromatography

Retention factors in reversed-phase high-performance liquid chromatography (RP-HPLC) were utilized for the analysis of complex formation reaction of four crown ethers with potassium ion in water-methanol media. The crown ethers were injected as analytes, potassium ion was present in the eluent, and three types of reversed-phase columns were used. The retention factor of the crown ethers decreased with increasing concentrations of potassium ion in the eluent, which is attributed to the change in the species of the crown ether from a neutral ligand to a positively charged complex. The complex formation constants were determined by analyzing the changes in the retention factor with a non-linear least-squares method.


Determination of Nitrogen Dioxide in the Atmosphere by Microflow-Injection Absorptiometry with a Portable-Type Flow System after Batchwise Absorption Collection


Separation and Determination of Haloperidol, Parabens and Some of Their Degradation Products by Micellar Electrokinetic Chromatography

A micellar solution containing phosphate buffer, anionic surfactant, and water-miscible organic solvent was employed as a migration solution for the separation and the quantification of eleven analytes by micellar electrokinetic chromatography (MEKC): the analytes examined were haloperidol, methylparaben, ethylparaben, n-propylparaben, iso-propylparaben, n-butylparaben, iso-butylparaben, sec-butylparaben, 4-(4-chlorophenyl)-4-hydroxypiperidine, 4-fluorobenzoic acid and 4-hydroxybenzoic acid. In order to provide good separation between micelle and haloperidol, which showed strongest interaction with the micelle among the analytes, surfactant concentrations and organic modifier percentages were studied with phosphate buffer at pH 7.0. All the analytes were successfully resolved when 10 mM sodium dodecylsulfate and 15% ethanol were contained in the migration solution; the time window was very wide in the range from 14.8 to 65.5 min. Optimized applied voltage at 30 kV and capillary temperature at 45 degrees C enable analyze all compounds in less than 17 min with the best resolution, the shorter migration time window, the highest precision and lowest detection limit.


Ion Association Reactions in Aqueous Solutions between Non-UV-Absorbing Crown Ether-Alkali Metal Complexes with Picrate Ion by Capillary Zone Electrophoresis


Analysis of Reactions of Aromatic Anions with Quaternary Ammonium Ions in Ion Association-Nonionic Micellar Electrokinetic Chromatography


Simultaneous Determination of Trace Elements in River-Water Samples by ICP-MS in Combination with a Discrete Microsampling Technique after Enrichment with a Chitosan-Based Chelating Resin


Analysis of Ion Association Reactions in Aqueous Solutions between Alkali Metal-Crown Ether Complexes and Pairing Anions by Capillary Zone Electrophoresis


Analysis of Ion Association Reactions between Monovalent Polycyclic Aromatic Cations and Anions in Aqueous Solution as Studied by Capillary Zone Electrophoresis


Simultaneous Determination of Lanthanoids and Yttrium in Rock Reference Samples by Inductively Coupled Plasma-Mass Spectrometry Coupled with Cation Exchange Pretreatment


Determination of Trace Elements in Water Samples by Inductively Coupled Plasma-Mass Spectrometry Connected with Air Flow- and Water Flow-Injection Techniques


Equilibrium Analysis of Reactions between Aromatic Anions and Nonionic Surfactant Micelles by Capillary Zone Electrophoresis

Separability of some positional isomers of aromatic anions by capillary zone electrophoresis was improved by adding nonionic surfactants to a migrating solution. Eleven kinds of aromatic anions, including positional isomers, were used as analytes, and Brij-35, Brij-58 and Brij-78 were investigated as nonionic surfactants to form micelles, where hydrophobicities are different from each other. Increasing the concentration of the surfactants developed the separability of the anionic isomers. The interaction between the anions and the nonionic surfactant micelles is also investigated through the change in the electrophoretic mobility, and the binding constants are determined. Apparent electrophoretic mobility of the anions decreased with increasing concentrations of the nonionic surfactants. The decrease in the mobility, as well as the binding constant, was larger in the monovalent anions than in the divalent anions, which indicates that the interaction or reactivity of the monovalent analytes is higher than that of the divalent analytes. The reactivity of each anion was almost identical even when the kinds of the surfactants were changed, suggesting that the hydrophobicity of the polyoxyethylene group in the surfactant would have the main role for binding the analytes. The reactivity tendency among the positional isomers was almost similar to that in ion association-capillary zone electrophoresis using tertabutylammonium ion as a pairing ion. The results obtained in this work suggest that the anions are bound to the micelles by the hydrophobic interaction between analyte anions and the polyoxyethylene moiety of the surfactant micelles. Changes in the fluorescence intensity of the anions were also investigated; the results can explain well the mobility changes of the analytes.


Electrophoretic Mobility Study on Ion-Ion Interactions in an Aqueous Solution


Ion Association of Primary Ammonium Ions with Aromatic Anions by Capillary Zone Electrophoresis

Bulletin of the Chemical Society of Japan


環境中の窒素，リン，硫黄化合物のオンサイト化学分析:マイクロフローインジェクション法による高感度定量


Analysis of Reactions between Crown Ethers and Alkali or Alkaline Earth Metal Cations in Aqueous Solutions by Capillary Zone Electrophoresis


Ion-Association Study of Methyl Orange Analogues with Quaternary Ammonium Ions in Aqueous Solution by Capillary Zone Electrophoresis


Separation of Inorganic Anions for Analysis of Sea-Water by Capillary Zone Electrophoresis


Direct Photometric Determination of Tungstate Ion in the Etching Solutions by Capillary Zone Electrophoresis


非イオン界面活性剤ミセル存在下におけるトリフェニルメタン系陽イオン染料からトリフェニルメタノール生成の速度論的研究


Analysis of Ion Association Reaction between Crown Ether Complexes of Alkali Metal Ions and Hydrophobic Anions by Capillary Zone Electrophoresis


Equilibrium Study on the Ion Association of Monovalent and Divalent Naphtholsulfonates with Tetrabutylammonium Ion in an Aqueous Solution by Capillary Zone Electrophoresis


Capillary Zone Electrophoretic Separation of Aromatic Anions Utilizing Enhanced Ion Associability with Viologen Cations


Separation of Divalent Aromatic Anions by Capillary Zone Electrophoresis Using Multipoint Ion Association with Divalent Quaternary Ammonium Ions


Thermodynamic Study of Ion-Association Reactions between Aromatic Anions and Tetrabutylammonium Ion in an Aqueous Solution


キャピラリー電気泳動法による第四級アンモニウムイオンと一価有機酸イオンとのイオン会合反応の解析


Ion Association Reaction between Divalent Anionic Azo Dyes and Hydrophobic Quaternary Ammonium Ions in Aqueous Solution as Studied by Capillary Zone Electrophoresis


Electrophoretic Mobility Study of Ion Association between Aromatic Anions and Quaternary Ammonium Ions in Aqueous Solution


Separation and Direct Photometric Determination of Inorganic Anions by Capillary Zone Electrophoresis Using Suppressed Electroosmosis


硫酸イオンの試料イオンに対するスタッキング効果を利用する無機陰イオンのキャピラリー電気泳動/直接吸光分析


Ion-Associate Solvent Extraction and Separation of Lanthanides(III) with 2,3-Naphthalenediol and Benzyldimethyltetradecylammonium Chloride

Bulletin of the Chemical Society of Japan


高速液体クロマトグラフィー四重電極型検出システムのセットアップ作業報告

高速液体クロマトグラフィー四重電極型検出システムのセットアップ作業報告

徳島大学技術支援部技術報告

徳島大学技術支援部技術報告


Flow Injection Analysis: its name do agree with its nature


可搬型環境試料中重金属濃度分析計の高機能化―セレン(IV)のマイクロカラム着色に基づく目視蛍光定量法の開発―

Bulletin of Institute of Technology and Science, The University of Tokushima

徳島大学大学院ソシオテクノサイエンス研究部研究報告


Analysis of Binding Reactions of Ionic Substances to Nonionic Surfactant Micelles

Solvent Extraction: Fundamental to Industrial Applications


Separation and Determination of Alkane Diamines by Capillary Electrophoresis Using Salicylaldehyde Sulfonate as a Derivatizing Reagent


Separation of Aromatic Substances by Micellar Electrokinetic Chromatography Using Surfactants Possessing Polyoxyethylene Moiety


A Mechanistic Study on Ion Association Extraction with Quaternary Ammonium Ions


Equilibrium Analysis of Crown Ether Complexes by Capillary Zone Electrophoresis

The Journal of Microcolumn Separations : JMS


Separation of Various Positional Isomers of Aromatic Anions by Nonionic Micellar Electrokinetic Chromatography Coupled with Ion Association Distribution


Ion Association Study in Aqueous Solution Using Capillary Electrophoresis


Extraction Removal of Transition Metal Ions from Lanthanides with 5,7-dimethyl-8-quinolinol

Proceedings of Symposium on Solvent Extraction


Inhibition Assay of Theophylline by Capillary Electrophoresis/Dynamic Frontal Analysis on the Hydrolysis of p-Nitrophenyl Phosphate with Alkaline Phosphatase


Equilibrium Analysis of Acid Dissociation Reactions of Phenolphthalein by Using Mobility Change in Capillary Zone Electrophoresis


Novel Approach to the Reaction Analysis of Non-UV-Absorbing Crown Ether with Alkali Metal Ions in Aqueous Solution by Capillary Zone Electrophoresis Using Indirect Photometric Detection


Analysis of Ion Association Property of Aromatic Divalent Anions with Quaternary Ammonium Ions in Aqueous Solution through Mobility Change of Capillary Electrophoresis


5,7-Dimethyl-8-Quinolinol as a Specific Non-Extracting Reagent for Lanthanide Ions at Usual pH Region