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Volume 55, Issue 1
Displaying 1-9 of 9 articles from this issue
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Research Paper
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Naoya OHMURA, Thomas R. GLASS, Kazuhiro SASAKI, Takashi JOH, Yukihiro ...2006 Volume 55 Issue 1 Pages 1-7
Published: 2006
Released on J-STAGE: April 10, 2006
JOURNAL FREE ACCESSA 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.
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Technical Paper
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Seiichi UENO, Tatsumi KITAMURA, Miki NAKAMURA, Keiko OZONE, Mutsuo ISH ...2006 Volume 55 Issue 1 Pages 9-13
Published: 2006
Released on J-STAGE: April 10, 2006
JOURNAL FREE ACCESSDiphenylarsinic 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).
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Shintaro NOZAWA, Kenichi SAKAIDA, Tadanao SUZUKI, Akemi YASUI2006 Volume 55 Issue 1 Pages 15-21
Published: 2006
Released on J-STAGE: April 10, 2006
JOURNAL FREE ACCESSThe 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.
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Hisatake NARASAKI2006 Volume 55 Issue 1 Pages 23-27
Published: 2006
Released on J-STAGE: April 10, 2006
JOURNAL FREE ACCESSThe 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.
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Masahiko NUMATA, Takashi YARITA, Yoshie AOYAGI, Misako YAMAZAKI, Yoko ...2006 Volume 55 Issue 1 Pages 29-40
Published: 2006
Released on J-STAGE: April 10, 2006
JOURNAL FREE ACCESSAn 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.
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Note
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Seiichi UENO, Tatsumi KITAMURA, Miki NAKAMURA, Keiko OZONE, Yasuyuki S ...2006 Volume 55 Issue 1 Pages 41-44
Published: 2006
Released on J-STAGE: April 10, 2006
JOURNAL FREE ACCESSA 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 μm 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.
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Analytical Report
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Makoto INADA, Takefumi SHIMIZU, Nobuhiro IKEI2006 Volume 55 Issue 1 Pages 45-49
Published: 2006
Released on J-STAGE: April 10, 2006
JOURNAL FREE ACCESSA 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.
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Tomoko HARAGA, Yutaka KAMEO, Mikio NAKASHIMA2006 Volume 55 Issue 1 Pages 51-54
Published: 2006
Released on J-STAGE: April 10, 2006
JOURNAL FREE ACCESSA 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.
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Satoko TANAKA, Kenji CHAYAMA2006 Volume 55 Issue 1 Pages 55-59
Published: 2006
Released on J-STAGE: April 10, 2006
JOURNAL FREE ACCESSThe 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.
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