Vol. 55 No. 1
January, 2006
Naoya Ohmura1, Thomas R. Glass1, Kazuhiro Sasaki1, Takashi Joh2, Yukihiro Taemi2 and Naoyuki Yokobori3
1 Central Research Institute of Electric Power Industry, Environmental Science Research Laboratory, 1646, Abiko, Abiko-shi, Chiba 270-1194(Received 22 September 2005, Accepted 26 October 2005)
A simple and rapid preparation procedure of PCBs in transformer oil in conjunction with an immunoassay using an automated instrument for detecting PCBs is described. The joint column is used to prepare PCBs. The oil sample is introduced into a primary diatomite column containing fuming sulfuric acid and sulfuric acid to degrade the hydrocarbons, besides PCBs; the resulting hydrocarbons are removed by a secondary silica column. PCBs in the elusion are then extracted by dimethyl sulfoxide for an immunoassay. This preparation procedure can be performed within 30 min., and the recovery ratio of PCBs is estimated to be in the range from 40% to 60%. PCBs can be detected with an automated immunoassay instrument after mixing the dimethyl sulfoxide extract at 1%(v/v) with an anti-PCB antibody solution. The assay is completed within 8 min. The dynamic range is, respectively, from 0.3 ppm to 18 ppm for Kanechlor 300, from 0.2 ppm to 0.7 ppm for Kanechlor 400, and from 0.1 ppm to 1.5 ppm for Kanechlor 500 and 600. This assay also enables one to detect PCBs as a total in fifteen oil samples in the range from 0.1 ppm to 1.8 ppm with a good correlation with the analysis using a high-resolution mass spectrometer.
Keywords : PCB; immunoassay; transformer oil; rapid detection.
Seiichi Ueno1, Tatsumi Kitamura1,2, Miki Nakamura1, Keiko Ozone1 and Mutsuo Ishizaki1,3
1 Ibaraki Prefectural Institute of Public Health, 993-2, Kasahara-cho, Mito-shi, Ibaraki 310-0852(Received 19 May 2005, Accepted 14 September 2005)
Diphenylarsinic acid (DPAA) was extracted selectivity and efficiently from biological samples by a combined solvent extraction with solid-phase extraction and was determined by graphite-furnace atomic-absorption spectrometry (GFAAS). After 0.01~0.1 g of biological samples were decomposed in 1 ml of 2 M sodium hydroxide by heating (90~120°C, 2~5 h), 1 ml of water was added. The decomposed solution was shaked for 5 min with 1 ml of chloroform and 4 ml of n-hexane, and the organic layer was discarded. The aqueous layer was adjusted to ca. 0.5 M hydrochloric acid solution by the addition of 2 ml of 2 M hydrochloric acid, and 1 ml of 20% cysteine solution and 1 ml of 40% potassium iodide solution were added to this solution. After 30 minutes, DPAA was extracted with 4 ml of chloroform. This operation was repeated again and combined chloroform layers were evaporated. After the residue was dissolved in 0.5 ml of ethanol, 10 ml of a 1% nitric acid solution was added and mixed well. The mixture was then passed through a 0.45 µm of membranefilter and 0.2 ml of a 0.05 M EDTA solution was added to the filtrate. The solution was applied on an Oasis HLB cartridge and DPAA was eluted in 6 ml of ethanol. After evaporation of the solvent, the residue was dissolved in 1 ml of water and DPAA was analyzed by GFAAS. The proposed method could determine DPAA in biological samples, such as mouse brain, liver and kidney with an average recovery of 93%. The coefficient of variation was as low as 15%. The calibration curve was linear between 0 and 50 ng/ml (r=0.999).
Keywords : determination of diphenylarsinic acid; biological samples; solvent extraction; solid-phase extraction; graphite-furnace atomic- absorption spectrometry.
Shintaro Nozawa1, Kenichi Sakaida1, Tadanao Suzuki2 and Akemi Yasui2
1 Center for Food Quality, Labeling and Consumer Services, 2-1, Shintoshin, Chuo-ku, Saitama-shi, Saitama 330-9731(Received 10 February 2005, Accepted 21 September 2005)
The determination of total nitrogen in soy sauce by the Kjeldahl method using traditional digestion and distillation, or using block digestion and steam distillation, has been studied as a candidate to be proposed to the Codex Alimentarius Commission. In order to obtain the optimum digestive condition, the added amounts of H2SO4, K2SO4 and CuSO4·5H2O catalysts, the way of adding the catalyst, and the boiling period after the liquid became clear were examined. The optimum conditions for the digestion of 1 ml soy sauce were found to be adding 10 ml of H2SO4, 10 g of K2SO4, and 1 ml of 20% CuSO4·5H2O, and boiling for 80 min after a clear liquid is obtained in traditional digestion. Eight grams of K2SO4 were found to be appropriate in block digestion. Samples were measured by weight, and the total nitrogen was calculated on a % (w/w) basis to avoid the effect of the soy sauce viscosity. The nitrogen content was converted into % (w/v) by using the density of each sample. These sampling and digestion methods were compared with the JAS grading method for three kinds of soy sauce, lysine and (NH4)2SO4 solutions. The results yielded a significantly higher nitrogen content in full-bodied soy sauce; also, the recoveries (98 to 100%) for lysine and (NH4)2SO4 solutions, had lower RSD values than did that of the JAS grading method, and were regarded as being more accurate.
Keywords : Codex; soy sauce; Kjeldahl; digestion; distillation.
Hisatake Narasaki1
1 Saitama-ken Environmental Analysis and Research Association, 1450-11, Kamiko-cho, Omiya-ku, Saitama-shi, Saitama 330-0855(Received 20 July 2005, Accepted 30 September 2005)
The recovery of Dalapon (2,2-dichloropropionic acid) in water samples was checked by liquid chromatography/mass spectrometry. Pure, tap and river-water samples (50 ml) were saturated with 15 g of sodium chloride and acidified with 3 ml of 9 M sulfuric acid. The samples spiked with 100 ng each of Dalapon were extracted with 3 ml of methyl t-butyl ether (MTBE) using a mechanical shaker for 10 min. The MTBE extracts were evaporated to 1 ml by a stream of nitrogen gas. The concentration of Dalapon was determined by isocratic-mode liquid chromatography, and the negative mode by electrospray ionization. The mass spectrograms of Dalapon at m/z 141 and 105 appeared at a retention time of 4.6 min. The recoveries of Dalapon ranged from 67 to 101%. The detection limits (concentrations at signal-to-noise ratio 3) of Dalapon at m/z 141 and 105 were 2.1 and 3.8 ng ml-1 in the working curve, respectively.
Keywords : Dalapon; solvent extraction; tap water; river water; electrospray ionization; liquid chromatography/mass spectrometry.
Masahiko Numata1, Takashi Yarita1, Yoshie Aoyagi1, Misako Yamazaki1,
1 National Metrology Institute of Japan (NMIJ), National Institute of Advanced Science and Technology (AIST), Tsukuba Central 3-10, 1-1-1, Umezono, Tsukuba-shi, Ibaraki 305-8563(Received 25 July 2005, Accepted 24 October 2005)
An analytical method for the determination of persistent organic pollutants in biological tissues by using pressurized fluid extraction (PFE), followed by isotope-dilution gas chromatography/mass spectrometry, has been established. We participated in international comparisons (CCQM-P40, 57, 67) on the determination of organic contaminants in mussel (Mytilus edulis) tissue between national metrology institutes by using an analytical method. Details of our results for the determination of the target compounds (five polychlorinated biphenyl congeners, two pesticides and five polycyclic aromatic hydrocarbons) are described in terms of a quantification procedure using an equation that has been used to describe the isotope-dilution method, and an evaluation of the uncertainties of the measurement. Some results of the international comparisons are also given, in which our results are comparable to those reported by a majority of the participants.
Keywords : POPs analysis; biological tissue; mussel (Mytilus edulis); international comparison (CCQM-P40, P57, P67); polychlorinated biphenyls; organochlorine pesticides; polyaromatic hydrocarbons; pressurized fluid extraction; isotope-dilution mass spectrometry.
Seiichi Ueno1, Tatsumi Kitamura1,2, Miki Nakamura1, Keiko Ozone1, Yasuyuki Shibata3 and Mutsuo Ishizaki1,4
1 Ibaraki Prefectural Institute of Public Health, 993-2, Kasahara-cho, Mito-shi, Ibaraki 310-0852(Received 19 May 2005, Accepted 21 September 2005)
A method for the determination of diphenylarsinic acid (DPAA) in plants and biological samples by high-performance liquid chromatography-tandem mass spectrometry (HPLC/MS/MS) using a stable isotope labeled compound as an internal standard is described. After the sample was decomposed in 2 M sodium hydroxide by heating, an internal standard (DPAA-13C12) was added to the solution. The decomposed solution was shaked with a mixture of chloroform and n-hexane (1 : 4). After centrifugal separation, the organic layer was discarded. The aqueous layer was then adjusted to ca. 0.5 M hydrochloric acid solution, and cysteine and potassium iodide were added in order to extract DPAA efficiently in the chloroform. Extraction was carried out twice, and the chloroform layers were combined and evaporated. The extracts were dissolved in methanol or water in case of plants. When a colored solution was obtained, it was purified by an Oasis HLB solid-phase cartridge. In biological materials, the extracts were dissolved in a small volume of methanol, and then 0.5% nitric acid solution was added. When the mixture got cloudy, it was passed through a 0.20 mm of membranfilter. DPAA in the final solution was analyzed by HPLC/MS/MS. HPLC separation was performed with an ODS column using a linear gradient elution of an acetonitrile-water system containing 0.1% trifluoroacetic acid as the mobile phase. MS/MS was used in multiple reaction monitoring (MRM), employing electrospray ionization. The proposed method could determine DPAA in plants and biological samples with an average recovery of 99.4%. The coefficient of variation was as low as 6%. The calibration curve was linear between 0 and 30 ng/ml.
Keywords : determination of diphenylarsinic acid by high-performance liquid chromatography-tandem mass spectrometry; plants and biological samples; solvent extraction; stable isotope labeled compound.
Makoto Inada1, Takefumi Shimizu1 and Nobuhiro Ikei1
1 Diagnostics Division, Otsuka Pharmaceutical Co., Ltd., Kawauchi-cho, Tokushima-shi, Tokushima 771-0182(Received 16 June 2005, Accepted 1 October 2005)
A validation study of the DPD activity measurement was carried out using peripheral mononuclear cells obtained from two healthy male adults. As a result, the DPD activity was 450.2 pmol/min/mg protein (mean value of 5 measurements), the intra-day reproducibility (C.V. intra.) was 12.5%, and the inter-day reproducibility (C.V. inter.) was 24.5%, indicating rather large deviations. The mean of the recovery rate in this study was, however, 100.4%, which is almost 100%, and the deviation (C.V.=4.2%) was small. The HPLC apparatus and the analysis devices worked with good precision and reproducibility. It could be predicted that the DPD activity values might vary during the collecting process of monocytes. A large variation might have resulted from the large variance in the cellular composition of the mononuclear cell fraction.
Keywords : dihydropyrimidine dehydrogenase activity; mononuclear cells in peripheral blood.
Tomoko Haraga1, Yutaka Kameo1 and Mikio Nakashima1
1 Japan Atomic Energy Agency, 2-4, Shirakata-Shirane Tokai-mura, Naka-gun, Ibaraki 319-1195(Received 9 August 2005, Accepted 15 October 2005)
A relatively large quantity of sample solutions have to be prepared for the radiochemical analysis of solidified products yielded by a plasma melting treatment of non-metallic radioactive wastes. In order to dissolve a sample of solidified products rapidly, a dissolution method with microwave heating devices was applied. In a conventional method involving only external heating with various mixtures of acids (HNO3, HF, HClO4 and H2SO4), a 0.1 g amount of the sample was dissolved with difficulty. However, upon applying the microwave-assisted dissolution method, a 1 g amount of the sample was completely dissolved in a shorter time. Thereby the time for dissolution procedures was shortened to less than one-tenth. The present dissolution method was successfully applied to blast furnace slag as a reference material to determine the main elements with good precision.
Keywords : microwave heating; rapid dissolution techniques; non-metallic wastes; solidified products; plasma melting.
Satoko Tanaka1 and Kenji Chayama2
1 Kobe Women's Junior College, Department of Food and Nutritional Science, 4-7-2, Minatojimanakamachi, Chuou-ku, Kobe-shi, Hyogo 650-0046(Received 23 February 2005, Accepted 1 November 2005)
The determination of the mineral contents, in some commercially available tofu by atomic absorption spectrophotometry and flame spectrophotometry was examined. The mineral contents in Kinugoshi and Momen -tofu were compared with the values of the standard table of food composition. It was found that the contents of minerals were higher than the values of the table, except that Ca values was lower. Comparing the mineral contents between the Kinugoshi and Momen -tofu, contents of Na, K, and Mg were higher in the Kinugoshi -tofu, and contents of Fe, Zn, and Ca were higher in the Momen -tofu. This fendency was consistent with the table with the exception of Na.
Keywords : tofu; mineral; wet digestion; atomic absorption spectrophotometry; flame spectrophotometry.
Shin-Ichi Ohira
Department of Environmental Science, Faculty of Science, Kumamoto University, 2-39-1, Kurokami, Kumamoto-shi, Kumamoto 860-8555
(Awarded by Kumamoto University dated March 25, 2005)
New systems have been developed for continuous and semi-continuous determinations of atmospheric trace gases. Analyte gases are collected into absorbing solutions at miniature diffusion scrubbers to concentrate, and the analytes are in-situ or subsequently measured. The systems are suitable for on-site measurement in the fields. Simultaneous and large dynamic range determinations of hydrogen sulfide, methanethiol and sulfur dioxide were performed with annular diffusion scrubbers. This system was applied for field measurement on the head-space of septic tank and the crater of Mt. Aso. A porous tube filled with an absorbing solution worked as a good waveguide and collector. By using this porous tube collector/Long path absorbance detector, we achieved sub-ppbv detection limits within a few minutes for nitrogen dioxide and ozone. A flat scrubber had only 800 nl cell integrated with microfabricated platinum electrodes for in-situ conductivity detection. This can determine sulfur dioxide at a higher time resolution than commercial instrument. A microchannel scrubber has been developed for high collection and low achieved solution consumption. Not only the diffusion scrubber, but also whole system included detector, sampling and liquid flow system were downsized and integrated. This system was proposed as the micro gas analysis system, µ-GAS.
(Received August 17, 2005)
Keywords : diffusion scrubber; sulfur gases; µ-GAS.
Nobumitsu Niina
Department of Applied Science, Okayama University of Science, 1-1, Ridaicho, Okayama-shi, Okayama 700-0005
(Awarded by Okayama University of Science dated March 20, 2005)
Simultaneous detection methods have not been developed with the exception of conductivity method connected ion exchange chromatography, although various detection methods corresponded to each amines have been needed for obtaining the pri-, sec-, and tert-amine moiety in structures. The author has developed three HPLC systems for the simultaneous detection amine compounds, based on online reaction. 1) Online derivatization and chemiluminescence reaction system; pri- and sec-amine compounds are derivatized to tert-amine compound(s) by epichlorohydrin, the following the tert-amine compound(s) is detected by chemilumenescence reaction of [RuIII(bpy)3]3+ and a CL detector. 2) An online oxidation and Griess reaction system; amine compounds are oxidized to nitrogen oxides by oxidation reagent and UV irradiation to promote of the reaction. And nitrite ions in the nitrogen oxides are used as a detection probe, and are detected by the Griess reaction. 3) Online oxidation reaction and OPA fluorescence reaction system; the nitrogen oxides generated from amine compounds by online oxidation are reduced to NH3 on the reduction column packed with zinc powder. And the NH3 as a detection probe is detected by OPA fluorescence reaction and a fluorescence detector. The simultaneous detection was proposed by these detection systems proposed in this study.
(Received August 29, 2005)
Keywords : simultaneous detection; amine compound; online reaction; ruthenium(III); bipyridine complex; chemiluminescence; Griess reaction; HPLC.
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