Amplitude modulated flow analysis for speciationProof of concept by quantification of Fe2+ and Fe3+ ions


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


Humic-Like Substances Global Levels and Extraction Methods in Aerosols


Diurnal variations in partitioning of atmospheric glyoxal and methylglyoxal between gas and particles at the ground level and in the free troposphere


Dry Mechanochemical Synthesis of Caffeine/Oxalic Acid Cocrystals and Their Evaluation by Powder X-Ray Diffraction and Chemometrics

We report the effects of dry mechanochemical synthesis conditions on the crystallization of caffeine (CA) and oxalic acid (OX) 2:1 cocrystal. CA anhydrate and OX dihydrate were grinded at various temperatures, rotation speeds, and grinding time. The cocrystal was also synthesized by an organic solvent evaporation method, as a reference. The produced samples were measured by a powder X-ray diffraction (PXRD) analysis. The PXRD spectra suggest that the grinded cocrystal has a lower crystallinity than the evaporated one. The diffractograms for the cocrystals synthesized by 2 kinds of methods were further evaluated by multivariate curve resolution-alternating least squares method. Sources of the mathematical models constructed were assigned to the cocrystal and unreacted mixture of CA and OX dihydrate. The present approach is concluded to be useful for the improvement of pharmaceutical property because cocrystallization is closely relating to the solubility characteristics, bioavailability, stability, and so on of drugs.


Mechanochemical synthesis of chloroapatite and its characterization by powder X-ray diffractometory and attenuated total reflection - infrared spectroscopy


High Time-Resolution Monitoring of Free-Tropospheric Sulfur Dioxide and Nitric Acid at the Summit of Mt. Fuji, Japan


クリーンルーム雰囲気中のアンモニア及びアミンガスを監視するウエットデニューダ方式の自動モニタ


Quantification of pharmaceutical compounds based on powder X-ray diffraction with chemometrics

We propose an approach for the simultaneous determination of multiple components in pharmaceutical mixed powder based on powder X-ray diffraction (PXRD) method coupled with chemometrics. Caffeine anhydrate, acetaminophen and lactose monohydrate were mixed at various ratios. The samples were analyzed by PXRD method in the ranges of 2=5.00-30.0 and 35.0-45.0 degrees. Obtained diffractograms were analyzed by conventional peak intensity method, multi curve resolution (MCR)-alternating least squares (ALS) method and partial least squares (PLS) method. Constructed PLS models can most accurately predict the concentrations among different methods used. Each regression vector of PLS correlates not only to the compound of interest but also to the coexisting compounds. The combination of PXRD and PLS methods is concluded to be powerful approach for analyzing multi components in pharmaceutical formulations.


Online Analysis of Water-soluble Acidic Gases and Anions in PM2.5 at Tokushima City in Winter of 2015

2015年冬季の徳島市における水溶性酸性ガス及びPM2.5に含まれる陰イオンのオンライン分析

This paper describes a simultaneous analytical system used for atmospheric water-soluble acidic gases and anions in PM2.5. The analytical system, consisting mainly of a parallel-plate wet denuder, mist chamber-hydrophobic filter based particle collector, and ion chromatograph provides automatically two acidic gas and two PM2.5 data with in one hour. We applied the system to the continuous measurement of air pollutants at Tokushima, Japan in the winter of 2015, and obtained meaningful data in 97.9 % of the sampling period. The average acidic gas concentration and anion concentration in the PM2.5 were, respectively, 4.85±3.08 nmol m-3 for HCl, 22.19±18.47 nmol m-3 for HONO, 9.54±2.52 nmol m-3 for HNO3, 101.57±71.99 nmol m-3 for SO2, 3.78±6.48 nmol m-3 for Cl-, 3.37±1.99 nmol m-3 for NO2-, 25.16±31.49 nmol m-3 for NO3-, and 92.61±55.33 nmol m-3 for SO42-. Characteristic diurnal patterns were observed in several gases. The concentration of HCl fluctuated with changes in the temperature with a 2-hour time-lag. The concentration of HONO peaked in the morning and middle of the night, and its behavior showed a similar pattern of NO2 concentration. Backward trajectory analysis suggested that a high concentration of SO2 that was emitted from China was transported to the sampling site, Tokushima, Japan.

大気中の水溶性酸性ガス及びPM2.5に含まれる陰イオン濃度を高い時間分解能で同時観測可能なオンライン分析システムを構築した．本分析システムは，主に自作のパラレル式ウエットデニューダーと疎水性フィルターを装着したミストチャンバー，及び陰イオン分析用のイオンクロマトグラフ1台で構成され，酸性ガスとPM2.5中陰イオンのデータを1時間にそれぞれ二つずつ出力する．本分析システムを2015年冬季の徳島市の大気分析に適用したところ，観測期間の97.9% で有益なデータを得ることができた．酸性ガス濃度の平均値(n＝844)は，それぞれHCl: 4.85±3.08 nmol m-3，HONO: 22.19±18.47 nmol m-3，HNO3 : 9.54±2.52 nmol m-3，SO2 : 101.57±71.99 nmol m-3であり，SO2が高濃度に存在していた．一方，PM2.5に含まれる陰イオンの平均値(n＝844)は，それぞれCl-: 3.78±6.48 nmol m-3，NO2-: 3.37±1.99 nmol m-3，NO3-: 25.16±31.49 nmol m-3，SO42-: 92.61±55.33 nmol m-3であり，これら陰イオンの総濃度の9割以上をSO42-とNO3-が占めていた．観測期間中の同時刻のデータを平均化して，観測成分の日内変動を調べたところ，いくつかの酸性ガスで特徴的な挙動が明らかとなった．HCl濃度は気温の変動と類似していたが，そこには2時間のタイムラグが存在した．HONO濃度は午前9時頃と深夜0時頃にピークを有する二山型の変動がみられ，その挙動はNO2濃度の変動と類似していた．また，観測データを後方流跡線解析と対応させることにより，中国大陸から排出された高濃度のSO2が徳島に流入している可能性が示唆された．


Cobalt(III) Pretreatment for Total Phosphorus Determination

Abstract: A fast and simple pretreatment method of phosphorus compounds using Co3+ has been studied for the spectrophotometric determination of total phosphorus in water samples. Sample was mixed with a pretreatment solution (0.05 mol dm-3 CoSO4 in 1 mol dm-3 H2SO4) in an electrolytic cell at the volume ratio of 4:1. Highly reactive Co3+ was continuously generated through the electrolysis of Co2+ during the pretreatment. Aliquot of the solution was injected to the system of flow injection - Molybdenum Blue spectrophotometry in order to evaluate phosphate ion (PO43-) produced. Organic phosphorus compounds are completely decomposed to PO43- within 2 min by Co3+ under moderate condition (70°C). The Co3+ is also effective for the acid hydrolysis of polyphosphates; diphosphate and tripolyphosphate are converted to PO43- within 8 min through the pretreatment. Possible mechanisms of the pretreatment are discussed based on the strong oxidizing activity and the Lewis acid nature of Co3+.


Effect of hydroxypropyl cellulosse and hydroxypropyl methylcellulose on carbamazepine polymorphic transformation; attenuated total reflectance-infrared spectroscopy and chemiinformatics analysis


Application of Air Segmented Amplitude Modulated Multiplexed Flow Analysis with Software-Based Phase Recognition to the Determination of Ammonium Ion in Water Samples


Effect of carbon dioxide on self-setting apatite cement formation from tetracalcium phosphate and dicalcium phosphate dihydrate; ATR-IR and chemoinformatics analysis


Nafion Membrane Tube-Based On-Line Concentrator. Application to Urinary Orotic Acid Determined by Suppressed Ion Chromatography

This paper describes the performance of suppressed ion chromatography coupled with a Nafion membrane tube-based on-line concentration technique for the determination of urinary orotic acid, which serves as a biochemical indicator for ornithine transcarbamylase deficiency. After the separation of the analyte by the chromatography, it is concentrated while the eluent flows through the Nafion membrane tube, meanwhile, a nitrogen gas flows outside the tube to remove the solvent. The peak of orotic acid was increased with increasing sample residence time, nitrogen gas flow rate, and concentration temperature. With the concentrator, the detection sensibility was improved, and the lower detection limit was obtained compared to that without the concentrator. The optimized system has successfully been applied to the determination of orotic acid in real urinary samples.


Formaldehyde Content of Atmospheric Aerosol

Formaldehyde (HCHO) is a highly soluble polar molecule with a large sticking coefficient and thus likely exists in both gaseous and particulate forms. Few studies, however, address particulate HCHO (HCHO(p)). Some report that HCHO(p) concentrations (obtained only with long duration sampling) are very low. The lack of data partly reflects the difficulty of specifically measuring HCHO(p). Long duration filter sampling may not produce meaningful results for a variety of reasons. In this work, gaseous HCHO (HCHO(g)) and (HCHO(p)) were, respectively, collected with a parallel plate wet denuder (PPWD) followed by a mist chamber/hydrophilic filter particle collector (PC). The PPWD quantitatively removed HCHO(g) and the PC then collected the transmitted aerosol. The collected HCHO from either device was alternately analyzed by Hantzsch reaction-based continuous flow fluorometry. Each gas and particle phase measurement took 5 min each, with a 10 min cycle. The limits of detection were 0.048 and 0.0033 μg m(-3), respectively, for HCHO(g) and HCHO(p). The instrument was deployed in three separate campaigns in a forest station in western Japan in March, May, and July of 2013. Based on 1296 data pairs, HCHO(p), was on the average, 5% of the total HCHO. Strong diurnal patterns were observed, with the HCHO(p) fraction peaking in the morning. The relative humidity dependence of the partition strongly suggests that it is driven by the liquid water content of the aerosol phase. However, HCHO(p) was 100× greater than that expected from Henry's law. We propose that the low water activity in the highly saline droplets lead to HCHO oligomerization.


Air Segmented-Amplitude Modulated Multiplexed Flow Analysis with Software-Based Phase Recognition. Determination of Phosphate Ion

Amplitude modulated multiplexed flow analysis (AMMFA) has been improved by introducing air segmentation and software-based phase recognition. Sample solutions, the flow rates of which are respectively varied at different frequencies, are merged. Air is introduced to the merged liquid stream in order to limit the dispersion of analytes within each liquid segment separated by air bubbles. The stream is led to a detector with no physical deaeration. Air signals are distinguished from liquid signals through the analysis of detector output signals, and are suppressed down to the level of liquid signals. Resulting signals are smoothed based on moving average computation. Thus processed signals are analyzed by fast Fourier transform. The analytes in the samples are respectively determined from the amplitudes of the corresponding wave components obtained. The developed system has been applied to the simultaneous determinations of phosphate ions in water samples by a Malachite Green method. The linearity of the analytical curve (0.0-31.0 mol dm(-3)) is good (r(2)>0.999) and the detection limit (3.3 ) at the modulation period of 30s is 0.52 mol dm(-3). Good recoveries around 100% have been obtained for phosphate ions spiked into real water samples.


Atmospheric Acid Gases in Tokushima, Japan, Monitored with Parallel Plate Wet Denuder Coupled Ion Chromatograph

During the summer of 2011 and winter of 2012, we continuously measured trace acid gas concentrations in Tokushima, Japan, using a parallel plate wet denuder coupled ion chromatograph. The average concentrations of hydrochloric acid (HCl), nitrous acid (HONO), nitric acid (HNO(3)), and sulfur dioxide (SO(2)) were, respectively, 0.54, 1.20, 1.17, and 3.22 g m(-3) in the summer, and 0.09, 1.06, 0.46, and 5.11 g m(-3) in the winter. In the summer, concentrations of all the acid gases increased after sunrise and showed a strong diurnal pattern with daytime maxima and nighttime minima, but the time at which concentration levels began to increase and the pace of increase differed among the acid gases. The concentration of HONO increased sharply immediately after sunrise, while concentrations of the other three gases began increasing about one and half hours later. SO(2) showed the fastest rate of increase, followed by HNO(3) and HCl. These differences were likely attributable to the formation processes of gaseous substances.


Surface Modified Annular Wet Denuder for the Collection of Water-Soluble Trace Gases


On-Line Measurement of Perchlorate in Atmospheric Aerosol Based on Ion Chromatograph Coupled with Particle Collector and Post-Column Concentrator

An automated analysis system has been developed for measuring perchlorate concentration in atmospheric aerosol. The perchlorate in aerosol sample, which has been collected with water mist in a hydrophobic filter/mist chamber based particle collector, is continuously preconcentrated. The matrix ions such as sulfate are subsequently removed from the preconcentrator. The remaining perchlorate is then analyzed on-line with an ion chromatograph in conjunction with a Nafion membrane tube based post-column concentrator. The sensitivity is increased by a factor of 7.7 with the post-column concentration technique. The proposed system has been successfully operated at Tokushima, Japan. The limit of detection is 0.35 ng/m(3) for 3 h sampling cycle. The perchlorate concentration in the atmospheric aerosol averaged 1.01±1.75 ng/m(3) (n=12).


Simultaneous Determination of Nitrite and Nitrate Ions by Air-Segmented Amplitude-Modulated Multiplexed Flow Analysis

The concept of amplitude-modulated multiplexed flow analysis has been extended to the simultaneous determination of multiple analytes in a sample. A sample solution containing nitrite and nitrate ions is delivered from two channels, but the flow rates are varied at different frequencies. One of the channels has a reduction column for converting nitrate ions to nitrite ions. Downstream, the absorbance of the diazo-coupling product is monitored after the merging of both solutions with a Griess reagent. The signal is analyzed by a fast Fourier transform (FFT) in real time. From the thus-obtained amplitude, a µmol dm(-3) level of the ions can be determined. The introduction of air bubbles is effective to reduce any axial dispersion, and hence to improve the sensitivity.


Parallel-Plate Wet Denuder Coupled Ion Chromatograph for Near-Real-Time Detection of Trace Acidic Gases in Clean Room Air

This paper describes the performance of our automated acidic (CH(3)COOH, HCOOH, HCl, HNO(2), SO(2), and HNO(3)) gases monitor utilizing a parallel-plate wet denuder (PPWD). The PPWD quantitatively collects gaseous contaminants at a high sample flow rate (8 dm(3) min(-1)) compared to the conventional methods used in a clean room. Rapid response to any variability in the sample concentration enables near-real-time monitoring. In the developed monitor, the analyte collected with the PPWD is pumped into one of two preconcentration columns for 15 min, and determined by means of ion chromatography. While one preconcentration column is used for chromatographic separation, the other is used for loading the sample solution. The system allows continuous monitoring of the common acidic gases in an advanced semiconductor manufacturing clean room.


Air-Segmented Amplitude-Modulated multiplexed Flow Analysis

Air-segmentation is applied to amplitude-modulated multiplexed flow analysis, which we proposed recently. Sample solutions, the flow rates of which are varied periodically, are merged with reagent and/or diluent solution. The merged stream is segmented by air-bubbles and, downstream, its absorbance is measured after deaeration. The analytes in the samples are quantified from the amplitudes of the respective wave components in the absorbance. The proposed method is applied to the determinations of a food dye, phosphate ions and nitrite ions. The air-segmentation is effective for limiting amplitude damping through the axial dispersion, resulting in an improvement in sensitivity. This effect is more pronounced at shorter control periods and longer flow path lengths.


Spectrophotometric Determination of Trace Phosphate Ion by Amplitude Modulated Flow Analysis Coupled with Malachite Green Method

An amplitude-modulated flow analysis coupled with lock-in detection is proposed for the determination of trace phosphate. The flow rate F(S) of sample solution is varied in response to a periodic signal V(c) of alternating waveform. A coloring reagent solution (ammonium molybdate + Malachite Green) is delivered at a constant flow rate F(R). Under the constant total flow rate F(T), both solutions are merged with a diluent (water). Phosphate ion in the sample reacts with molybdate and then with Malachite Green to form green ion pairs in acidic media. Downstream, the absorbance of the mixed solution is measured at 625 nm. The output voltage V(d) from the detector is sent to a lock-in amplifier, where the wave component of V(d) that has the same frequency as that of V(c) is distinguished from background signals. Phosphate ion can be determined from the amplitude of the component thus extracted. The calibration curve is linear (r(2) > 0.998) and the limit of detection (3.3sigma) is 0.17 micromol dm(-3). Compared with a conventional flow-based method with no modulation, the present method is less susceptible to the baseline drift due mainly to the adsorption of the ion-pair on the optical window, because the quantification is based not on the absorbance itself but on the amplitude of the absorbance. Good recoveries around 100% are obtained for the phosphate ions spiked into real water samples.


Analytical Parameters for Amplitude Modulated Multiplexed Flow Analysis

Analytical conditions of amplitude-modulated multiplexed flow analysis, the basic concept of which was recently proposed by our group, are investigated for higher sample throughput rate. The performance of the improved system is evaluated by applying it to the determination of chloride ions. The flow rates of two sample solutions are independently varied in accordance with sinusoidal voltage signals, each having different frequency. The solutions are merged with a reagent solution and/or a diluent, while the total flow rate is held constant. Downstream, the analytical signal V(d) is monitored with a spectrophotometer. The V(d) shows a complicated profile resulting from amplitude modulated and multiplexed information on the two samples. The V(d) can, however, be deconvoluted to the contribution of each sample through fast Fourier transform (FFT). The amplitudes of the separated wave components are closely related to the concentrations of the analytes in the samples. By moving the window for FFT analysis with time, a temporal profile of the amplitudes can be obtained in real-time. Analytical conditions such as modulation period and system configuration have been optimized using aqueous solutions of Malachite Green (MG). Adequate amplitudes are obtained at the period of as low as 5 s. At this period, the calibration curve for the MG concentration of 0-30 micromol dm(-3) has enough linearity (r(2) = 0.999) and the limit of detection (3.3sigma) is 1.3 micromol dm(-3); the relative standard deviation of repeated measurements (C(MG) = 15 micromol dm(-3), n = 10) is 2.4%. The developed system has been applied to the determination of chloride ions by a mercury(II) thiocyanate method. The system can adequately follow the changes in analyte concentration. The recoveries of chloride ion spiked in real water samples (river and tap water) are satisfactory, around 100%.


Atmospheric Methanethiol Emitted from a Pulp and Paper Plant on the Shore of Lake Baikal.


Dynamics of Sulfur-Containing Admixtures in the Atmosphere around the Point Source the Baikal Pulp and Paper Plant (South-East of Baikal Lake).


Spectrophotometric Determination of Anionic Sufactant Based on Ion-pair Formation with Methylene Blue in Riversed Flow Injection Mode


Application of Feedback-Based Flow Ratiometry to Simultaneous Determination of Calcium and Magnesium Ions by Chelatometry Using Photometric and Potentiometric Detectors


Use of a Capacitance Measurement Device for Surrogate Noncontact Conductance Measurement

A capacitance to digital converter (AD7746) is used in the same mode as noncontact conductance detectors. The detector output is linearly proportional to specific conductance (sigma) at low sigma values but becomes nonlinear and reaches a plateau value at sigma approximately >0.75 mS/cm, regardless of the nature of the electrolyte. For all applications at sub- to low-mM concentrations, the device, available as an evaluation board, provides a very affordable nothing-else-required means of contactless surrogate conductivity detection from capillary scale to larger bore conduits. For the same measurement cell volume, the detector provides virtually the same limits of detection (LODs) as a standard galvanic contact conductivity detector in conventional scale suppressed conductometric ion chromatography. The detection limits deteriorate as the conduit inner diameter decreases.


On-Line Gas-Free Electrodialytic Eluent Generator for Capillary Ion Chromatography.

Both low- and high-pressure, gas-free, capillary-scale electrodialytic generators for eluents in ion chromatography are described. While the low-pressure devices rely on planar or tubular membranes, the high-pressure devices rely on ion-exchange beads used both as one-way ionic gates and as ball-on-seat valves to provide sealing. The high-pressure device is easily implemented in the form of a commercial cross fitting and can withstand at least 1400 psi. By design these devices do not produce gas in the eluent channel; hence, it is not necessary to remove gas afterward. With appropriate electrolytes and electrode polarities, such devices can produce either acid or base or salt. In regard to ionic transport, the behavior of these devices fully corresponds to that of a semiconductor diode. To our knowledge, this is the first time such complete equivalence of ion transport through ion-exchange media and with the more familiar example of electron transport through a semiconductor diode under both forward- and reverse-biased conditions have been demonstrated. Reverse bias can be applied to minimize/prevent Donnan-forbidden leakage or ion exchange. Even with 4 M KOH in the electrode compartments and 4 microL/min water flowing through the eluent channel, with a reverse bias of -12 V, the leakage KOH concentration is <30 microM, whereas the KOH concentration with zero voltage applied, herein after termed open circuit penetration (OCP), is 1600 microM. It is suggested that this OCP occurs not as much through Donnan-forbidden leakage but via ion exchange. Chromatograms and reproducibility data are presented for both isocratic and gradient chromatography, using ion-exchange, latex-modified, open tubular and packed monolithic columns.


Amplitude Modulated multiplexed flow analysis


Postcolumn Concentration in Liquid Chromatography. On-Line Eluent Evaporation and Analyte Postconcentration in Ion Chromatography

On-line sample concentration by evaporation through a narrow-bore membrane tube is described. The device can be deployed just prior to the detector or the sample may be concentrated prior to injection. As solution flows through a solvent-permeable membrane tube, (heated) drying gas (nitrogen/air) flows outside it to remove the solvent. The removal rate increases with increasing sample residence time, drying gas flow rate, and temperature. Various membranes and three concentrator designs (a rectangular maze, a serpentine and a filament-filled helix, the last performing the best) were fabricated and tested for post- and preseparation applications in suppressed anion chromatography. An order of magnitude concentration factors are readily obtained. The present system involves active mass transport radially outward through the walls of a tube. This is a system in which many of the traditional paradigms of flow through a tubular conduit no longer hold true. Because the flow rate continuously varies along the tube, residence time does not scale linearly with residence volume or conduit length. The effects of such mass transport on the parabolic velocity profile of laminar flow remain unknown.


Tailoring elution of tetraalkylammonium ions. Ideal electrostatic selectivity elution order on a polymeric ion exchanger

Although ion exchange is often depicted as a process driven by electrostatic forces, ionic solvation or hydrophobic forces contribute greatly to ion exchange selectivity and is often the dominant factor. On a variety of commercial anion exchange columns, monovalent ClO4- elutes after doubly charged SO42- and even triply charged PO43-. For identically charged alkali metal ions, electrostatic charge densities based on crystal radii would suggest Li+ to be the most strongly retained on a cation exchanger. In practice, it is typically the least strongly held cation on most cation exchangers, because of its very high hydration energy and with most eluents its capacity factor approaches zero. Even when the ion is very poorly solvated, as with tetraalkylammonium (NR4+) cations, there has never been a report on a polymeric ion exchanger of an ideal electrostatic selectivity order where NR4+ cations elute in their increasing charge density order: R = n-butyl first, followed by n-propyl, ethyl, and last, methyl. We show that this selectivity order is easily achieved on recently described methracrylate-based monolithic capillary cation exchange columns (Ueki, Y.; Umemura, T.; Li, J. X.; Odake, T; Tsunoda, K. Anal. Chem. 2004, 76, 7007-7012) with minor amounts of hydroorganic modifiers. Indeed, under such conditions, Li+ (and other alkali cations) elutes after NMe4+.


Versatile gas/particle ion chromatograph

A new, compact gas/particle ion chromatograph has been developed for measuring ionic constituents in PM2.5 (particulate matter of aerodynamic diameter < or = 2.5 microm) and water-soluble ionogenic gases. The instrument has separate sampling channels for gases and particles. In one, a membrane denuder collects soluble gases for preconcentration and analysis. In the other, a cyclone removes larger particles, a membrane denuder removes soluble gases, and a continuously wetted hydrophilic filter collects particles. A single, multiport, syringe pump handles liquid transport, and one conductivity detector measures anions and ammonium for both channels. Electrodialytically generated gradient hydroxide eluent permits 20 min chromatographic runs. Gas/particle samples are each collected for 40 min, butthe sampling intervals are staggered by 20 min. Liquid samples from the gas denuder and particle collector are aspirated and preconcentrated on sequential cation and anion concentrators and transferred respectively to an ammonia transfer device and an anion separation column. The flow configuration results in an ammonium peak before anion peaks in the chromatogram. The system measures ammonia, organic acids (such as acetic, formic, and oxalic acids), HCl, HONO, SO2, HNO3, and the corresponding ions in the aerosol phase. Low ng/m3 to sub-ng/m3 limits of detection (LODs) are attained for most common gases and particulate constituents, the LODs for gaseous SO2 to NH3 range, for example, from sub parts per trillion by volume (sub-pptv) to approximately 5 pptv.


Continuous collection of soluble atmospheric particles with a wetted hydrophilic filter

Approximately one-third of the area (14-mm diameter of a 25-mm diameter) of a 5-microm uniform pore size polycarbonate filter is continuously wetted by a 0.25 mL/min water mist. The water forms a continuous thin film on the filter and percolates through it. The flowing water substantially reduces the effective pore size of the filter. At the operational air sampling flow rate of 1.5 standard liters per minute, such a particle collector (PC) efficiently captures particles down to very small size. As determined by fluorescein-tagged NaCl aerosol generated by a vibrating orifice aerosol generator, the capture efficiency was 97.7+% for particle aerodynamic diameters ranging from 0.28 to 3.88 microm. Further, 55.3 and 80.3% of 25- and 100-nm (NH4)2SO4 particles generated by size classification with a differential mobility analyzer were respectively collected by the device. The PC is integrally coupled with a liquid collection reservoir. The liquid effluent from the wetted filter collector, bearing the soluble components of the aerosol, can be continuously collected or periodically withdrawn. The latter strategy permits the use of a robust syringe pump for the purpose. Coupled with a PM2.5 cyclone inlet and a membrane-based parallel plate denuder at the front end and an ion chromatograph at the back end, the PC readily operated for at least 4-week periods without filter replacement or any other maintenance.


Characteristics of water-soluble components of atmospheric aerosols in Yokohama and Mt. Oyama, Japan from 1990 to 2001


Membrane based parallel plate denuder for the collection and removal of soluble atmospheric gases

A continuously wetted cellulose acetate membrane-based parallel plate diffusion denuder is described. This is the first membrane-based denuder that has a small enough internal liquid holdup volume to permit reasonably rapid response time (10 --> 90% rise time of approximately 1.2 min for a transient event at a liquid flow rate of 500 microL/min) while permitting quantitative removal of common soluble atmospheric trace gases at flow rates up to 1.7 L/min. The latter attribute permits the use of the device as the first element in a particle sampling and analysis system for the quantitative removal of potentially interfering soluble trace gases. Particle losses in the denuder range from 0.9 to 2.9% over an aerodynamic diameter range of 0.38-3.48 microm, averaging 1.8%. However, only approximately 0.5% of the particles actually appears in the denuder effluent liquid. The relatively compact (300 mm H x 57 mm W x 26 mm D) wet denuder should be attractive in a number of applications. We show excellent agreement for HONO measurements with a conventional larger parallel plate wetted denuder in field measurements.


Deposition of coarse soil particles and ambient gaseous components dominating dew water chemistry

Journal of Geophysical Research: Atmospheres


Size distribution of dew droplets and dew formation effect on deposition fluxes

Bulletin of the Chemical Society of Japan


Controlling factors of weak acid and base concentrations in urban dewwater -comparison of dew chemistry with rain and fog chemistry-


Dominant factors of major and minor components and formation of hydroxyalkanesulfonate in urban dew-water


A study on chemical components and acidification mechanism of dew-water

露水の化学組成とその酸性化機構に関する研究

Journal of Japan Society Atmospheric Environment