Vol. 54 No. 8
August, 2005
Yasuyuki Miura1
1 Department of Chemistry, Faculty of Science, Tokai University, Hiratsuka-shi, Kanagawa 259-1292(Received 29 March 2005, Accepted 16 May 2005)
Ion chromatographic methods were developed for the rapid separation and sensitive determination of trace sulfur anions in their mixtures: sulfide, sulfite, sulfate, thiosulfate, thiocyanate, dithionate and polythionates (tri-, tetra-, penta- and hexathionate) in water samples. The sulfur anions were resolved at short elution-times by: (1) ion-exchange chromatography, (2) ion-exclusion chromatography and (3) ion-pairing chromatography; (1) an anion-exchange column was used with an eluent of carbonate-1,3,5-benzenetricarboxylate (BTC), carbonate-acetonitrile and phthalate, (2) a column of cation exchanger of low crosslinking with diluted sulfuric acid mobile phase containing acetonitrile, and (3) a silica ODS column with acetonitrile-water mobile phase including tetra-n-propylammonium salt (TPA) of an ion-pairing reagent. The sulfur species in the effluent from the separating columns were measured by means of suppressed conductivity detection and UV photometry. Sensitive detection of the analyte, even when using phthalate eluent and carbonate eluent containing BTC, having strong eluting-power, was accomplished by a suppressed conductivity detection technique, because the benzenepolycarboxylate eluent ions could be converted to their acid forms of low conductivity on the suppressor. The sensitivity of determination of the sulfur anions was also increased by an indirect UV detection system using a postcolumn reaction, in which the residual iodine was measured as triiodide at 350 nm after reactions of the analytes (sulfide, sulfite and thiosulfate) with iodine, and iodine-azide reactions catalyzed by sulfide, thiosulfate, thiocyanate and polythionates (tri-, tetra-, penta- and hexathionate); their detection limits ranged from 10-7 to 10-6 M. Furthermore, a highly sensitive determination (detection limits of 10-8 M level) of thiosulfate, thiocyanate and four polythionates was achieved by the direct measurement of their absorbance at 230 nm, without any postcolumn reaction system. The proposed methods were successfully applied to the determination of sulfur anions of sulfide, sulfite, sulfate, thiosulfate and tetrathionate in hot-spring water samples. Their recoveries of thiosulfate and polythionates added to the water samples were also quantitative (96.0~104.3%).
Keywords : inorganic sulfur anions; ion chromatography; ion-exchange; ion exclusion; ion interaction; benzenecarboxylate; tetra-n-propylammonium salt; conductivity detection; photometric detection; postcolumn reaction; catalytic iodine-azide reaction.
Keiichi Fukushi1, Kuriko Yokota1,2, Yusuke Nakayama1,3, Nobuhiro Ishio1 and Takashi Miyado1,4
1 Faculty of Maritime Sciences, Kobe University, 5-1-1, Fukaeminami-machi, Higashinada-ku, Kobe-shi, Hyogo 658-0022(Received 22 March 2005, Accepted 26 May 2005)
We describe capillary zone electrophoresis (CZE) for the determination of trace inorganic anions in seawater. Bromide, nitrite, and nitrate were simultaneously determined using artificial seawater as the background electrolyte (BGE) without the interference of a high concentration of chloride in seawater. The proposed method was also applied to other environmental water samples, such as river water and rainwater samples, because the method was not affected by the salinity of samples. Then, highly sensitive CZE for nitrite and nitrate was established using transient isotachophoresis (TITP) as an on-line concentration procedure. The limits of detection (LODs) for nitrite and nitrate were 2.7 and 3.0 µg/l, respectively, at a signal-to-noise ratio of three. The values of the relative standard deviation (RSD) of the peak area for nitrite and nitrate were 2.0 and 0.75%, respectively, when the nitrite concentration was 0.05 µg/l and that of nitrate was 0.5 µg/l. The RSDs of the peak height were 4.4 and 2.3%. The RSDs of the migration time for these ions were 0.19 and 0.17%. The proposed method was applied to the determination of nitrite and nitrate in MOOS-1, a proposed certified reference material for nutrients in seawater distributed by the National Research Council of Canada (NRC, it is now sold as a seawater certified reference material for nutrients). The results for nitrite and the sum of nitrite and nitrate almost agreed with assigned tolerance intervals that were determined by NRC. Analytical results for nitrite and nitrate in coastal seawater samples taken from the surface and the seabed around the coastal area of Osaka Bay agreed with those obtained by naphthylethylenediamine spectrophotometry. In addition, another TITP-CZE method using phosphate as the terminating ion was developed for the simultaneous determination of iodide and iodate in seawater. The LODs for iodide and iodate were 4.0 and 5.0 µg/l. The RSDs of the peak area, peak height, and migration time for iodide and iodate were 2.9, 1.3, 1.0 and 2.3, 2.1, 1.0%, respectively.
Keywords : seawater analysis; nitrogen speciation; iodine speciation; capillary zone electrophoresis; transient isotachophoresis.
Masahiro Miyashita1 and Yoshiyuki Seyama1
1 Department of Clinical Chemistry, Hoshi University, 2-4-41, Ebara, Shinagawa-ku, Tokyo 142-8501(Received 22 March 2005, Accepted 26 May 2005)
Iodide ion (I-) is a hydrophobic anion that can be retained on reversed-phase columns. We determined I- by reversed-phase high-performance liquid chromatography without the use of ion-pairing reagents. I- was separated on a Hydrosphere C18 column using 50 mM ammonium phosphate (pH 4.0)-acetonitrile (95 : 5, v/v) as a mobile phase and detected with a UV detector at 225 nm. The calibration curve was linear over the range of 2.5×10-7~2.5×10-4 M and the limit of detection was 0.5×10-7 M (S/N=3). The relative standard deviations for six repeated determinations of 1.0×10-6, 1.0×10-5 and 1.0×10-4 M of I- were 1.7, 0.2 and 0.3%, respectively. This analytical method was applied to estimate the binding property of I- for ovalbumin.
Keywords : iodide ion; reversed-phase high-performance liquid chromatography; ultrafiltration.
Youhei Kawanaka1,2, Kazuhiko Sakamoto2, Ning Wang1 and Sun-Ja Yun1
1 The Institute of Basic Environmental Research, Environmental Control Center Co., Ltd., 323-1, Shimo-ongata, Hachioji-shi, Tokyo 192-0154(Received 25 February 2005, Accepted 9 June 2005)
We developed a highly sensitive, selective and simple method for the determination of six nitrated polycyclic aromatic hydrocarbons (nitroarenes; 2- and 3-nitrofluoranthene, 1-nitropyrene, 1- and 2-nitrotriphenylene and 6-nitrochrysene) and 3-nitrobenzanthrone (3-NBA) in atmospheric particulate matter (PM) by gas chromatography/tandem mass spectrometry with negative ion chemical ionization (GC/NCI-MS/MS). This method needs only silica gel column chromatography as a clean-up procedure. In order to separate the peaks of six nitroarenes and 3-NBA from the peaks of their isomers and matrices, we used two kinds of columns in GC/NCI-MS/MS analysis. The detection limits were 0.08~0.18 ng/ml for six nitroarenes and 0.07 ng/ml for 3-NBA. Recoveries of nitroarenes and 3-NBA added to PM samples were in the range of 92.6~106%. Five nitroarenes could be detected in atmospheric fine particles (PM2.0). Their concentrations were 81 pg/m3 for 2-nitrofluoranthene, 5.4 pg/m3 for 1-nitropyrene, 0.4 pg/m3 for 1-nitrotriphenylene, 0.4 pg/m3 for 6-nitrochrysene and 0.8 pg/m3 for 2-nitrotriphenylene.
Keywords : nitrated polycyclic aromatic hydrocarbons; nitroarene; 3-nitrobenzanthrone; GC/NCI-MS/MS.
Kunihiro Watanabe1, Naoki Imazato1 and Masayuki Itagaki1
1 Department of pure and applied chemistry, Faculty of Science and Technology, Tokyo University of Science, 2641, Yamazaki, Noda-shi, Chiba 278-8510(Received 8 February 2005, Accepted 22 June 2005)
A precision determination method of iron based on the formation of a stable iron complex was investigated by flow injection analysis (FIA). Four significant figures on the Fe content (%) could be obtained as the result of analysis by the present method, which was applied to the determination of iron in iron ores. Besides high precision, the results of Fe determination in standard iron-ores samples showed good agreement with certified values. The precision of the present method was equal to that of titration as the conventional method. The Fe complex formed in a line reaction tube with 1,2-dihydroxybenzene-3,5-disulfonic acid (Tiron) was detected by spectrophotometry at 667 nm. Tiron as the optimum detection reagent was selected based on the complex stability examined by using a stopped flow-meter, which could measure the absorbance with 6 significant figures, from among 4 kinds of conventional detective reagents. The absorbance obtained by UV-Vis spectrophotometry was recorded with 6 significant figures by Chromatomoniter with a personal computer. The channel flow system was examined concerning 4 kinds of manifold on the precision of the signal peak height and area. As a result, a single flow system was selected as the optimum manifold. A calibration curve was constructed by measuring the peak height of the absorbance signal. The optimum conditions of iron determination by the present method were as follows: sample solution (29.4 µl), pH 1.0; Tiron, 8.0×10-3 M, pH 5.0; flow rate, 0.5 ml/min; reaction coil length, 10 m; pump, double-plunger pump. A damper was used between the pump and the sample injector. The iron was determined over the range of 10 to 300 ppm by measuring a 1 : 1 complex of iron -Tiron. The RSD was 0.07% in the range of 150 to 300 ppm. The present method could be applied to iron ores containing above 55% iron. The throughput per hour was 6 for the sample solution.
Keywords : precision determination; iron ore; Tiron; single flow system; flow injection analysis.
Tatsumi Kitamura1,2, Seiichi Ueno1, Miki Nakamura1, Miyako Sibata1, Toshikazu Kaise3 and Mutsuo Ishizaki1,4
1 Ibaraki prefectural institute of public health, 993-2, Kasahara-cho, Mito-shi, Ibaraki 310-0852(Received 17 February 2005, Accepted 2 June 2005)
We measured diphenylarsinic acid (DPAA) in well water and seawater by solid-phase (SP) extraction, followed by graphite-furnace atomic-absorption spectrometry (GFAA). The sample solution was loaded on an Oasis® HLB cartridge activated by 5 ml of ethanol and 20 ml of distilled water. After washing with 15 ml of distilled water, DPAA was eluted with 6 ml of ethanol. The solvent was evaporated and the residue was dissolved in distilled water. This final solution (20 µl) was injected with a 0.025% magnesium solution (20 µl) into GFAA, and the DPAA concentration was determined. Other arsenic compounds, positive and negative ions and humic acid were also loaded to SP. When less than 1 mg of phenylarsonic acid was loaded, it was completely washed out before elution. Iron(III) reduced the recovery of DPAA, but it was improved by adding EDTA to the sample solution. The recoveries of DPAA in well water and seawater were 97% (C.V.=2.3%, n=5) and 102.7% (C.V.=3.4%, n=5), respectively. The detection limits of DPAA in well water and seawater were 0.028 ng/ml (0.008 ng/ml as arsenic) and 0.175 ng/ml (0.05 ng/ml as arsenic), respectively.
Keywords : diphenylarsinic acid; well water; seawater; solid-phase extraction; graphite furnace atomic absorption.
Takashi Miyawaki1, Ayato Kawashima1 and Katsuhisa Honda1
1 Enviromental Science for Industry, Faculty of Agriculture, Ehime University, 3-5-7, Tarumi, Matsuyama-shi, Ehime 790-8566(Received 22 March 2005, Accepted 4 June 2005)
A method consisting of supercritical fluid extraction with a solid-phase trap containing activated alumina was investigated for the simple analysis technique of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and coplanar PCBs (Co-PCBs) in soil. The soil sample was extracted using supercritical carbon dioxide with water (2% versus CO2 flow velocity) as an entrainer at 50 minutes, 30 MPa and 130°C. The extracts were adsorbed on an activated alumina trap held at 150°C, and thereafter dioxins were eluted with 20 ml of hexane at 60°C. The average concentrations of PCDD/DFs corresponded to the results of the conventional method, and the reproducibility of a replicate analysis was within 20% to the relative standard deviation. This new method is considered to be efficient for decreasing the analytical time (only 1 days) and reducing the analytical costs to be comparable to the conventional method.
Keywords : solid phase trapping; supercritical carbon dioxide extraction; dioxins; soil.
Ryo Koike1, Shoichi Jo1, Mikiko Azuma1 and Tatsushi Wakisaka1
1 Analytical Research Center, Kao Corporation, 1334, Minato, Wakayama-shi, Wakayama 640-8580(Received 4 February 2005, Accepted 21 June 2005)
A method based on proton nuclear magnetic resonance (1H-NMR) using an internal standard (IS) method was developed for the precise and simultaneous determination of surfactants. Quantitative analysis was performed by calculating the relative ratio of the integration between the characteristic signals of the target surfactants and a known amount of the IS in a 1H-NMR spectrum. By optimizing the combination of the solvent and IS, a simultaneous determination of various surfactants was achieved without any complicated separation procedures. In addition, a method for separating the overlapping signals in a spectrum was also investigated. The proposed method was applied to the determination of surfactants in consumer products, such as a heavy-duty liquid detergent and a fabric softener. As a result, several surfactants were simultaneously determined and the relative standard deviations were 0.13~0.46% (n=5). Furthermore, it was confirmed that the proposed method was also applicable to the simultaneous determination of various additives, such as a chelating agent and an alkaline agent, as well as surfactants.
Keywords : nuclear magnetic resonance (NMR); internal standard; determination; surfactants; consumer products.
Naoya Kimura1, Ken-ichi Ohno1,2 and Masaaki Yamada1
1 Department of Applied Chemistry, Graduate School of Engineering, Tokyo Metropolitan University, 1-1, Minami-Ohsawa, Hachioji-shi, Tokyo 192-0397(Received 31 March 2005, Accepted 21 June 2005)
Mixed-surfactant vesicles, which have the possibility of controlling the reaction pathways, formed from aqueous mixtures of octyltrimethylammonium chloride and sodium dodecanoate, were evaluated for a chemiluminescence (CL) reaction medium by means of a batch method. The lucigenin CL based on the oxidation by superoxide was chosen as a model CL system. The lucigenin CL intensity was enhanced by a factor of 65 in mixed vesicles (pH 9.2) compared with no use of a surfactant. This enhancement was greater than those in other ordered surfactant aggregates, and thought to be caused by the increased CL quantum yield, which resulted from a change in the reaction pathway in the mixed vesicular medium. The present lucigenin CL system can be used for the CL determination of biological analytes under nearly neutral conditions.
Keywords : chemiluminescence; mixed-surfactant vesicles; lucigenin; superoxide; hypoxanthine.
Susumu Sakata1, Katsuhiro Nakagawa2, Tadanobu Arimura3, Hisao Nakamura4, Greg Johnson5, Dan Wistrand5, Tetsuya Kimijima2, Masaru Yamazawa6 and Kazuhiro Shikakume6
1 Taiyo Nippon Sanso Corp., 498, Yokokurashinden, Oyama-shi, Tochigi 323-0819(Received 1 April 2005, Accepted 17 June 2005)
To confirm the reliability of trace-metal impurities analysis in industrial gases for semiconductors, a proficiency test was conducted for the analysis of sodium, chromium, manganese, iron and copper in a nitric acid solution at ppb levels. This testing was performed by comparisons between Japan and U.S. laboratories of the Taiyo Nippon Sanso Corporation (TNSC) Group jointly with the Chemicals Evaluation and Research Institute, Japan (CERI). The test samples provided by CERI were so stable that the relative standard deviations of the sodium, chromium, manganese, iron and copper concentrations were 7.3%, 0.3%, 2.0%, 0.4%, 2.7% for one and a half months, respectively. The test samples were delivered to three laboratories in Japan and the U.S. and analyzed by seven analysts and eight analytical instruments within one and half-month periods. Using a z score method, the reliability in the analysis of sodium, chromium, manganese and copper was generally confirmed. It was also confirmed that the analysis of iron was reliable enough, except for two data points provided by an analytical instrument and an analyst who did not normally perform metals analysis. Thus, these test results indicate that proficiency testing could evaluate the reliability of trace-metal impurities analysis precisely, and would be very useful in identifying trending errors in the analytical methods.
Keywords : proficiency testing; trace metal analysis; z score; industrial gas.
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