Vol. 55 No. 10
October, 2006
Teruhiko Kashiwabara1, Akiko Hokura1, Nobuyuki Kitajima1,2, Ryoko Onuma1, Hiroyuki Saito3, Tomoko Abe3 and Izumi Nakai1
1 Department of Applied Chemistry, Faculty of Science, Tokyo University of Science, 12-1, Hunagawaracho, Shinjuku-ku, Tokyo 162-0826(Received 5 July 2006, Accepted 16 August 2006)
Pteris vittata L. has come into use as a technology of phytoremediation due to its hyperaccumulation ability of As. The distributions of arsenic and potassium in roots were examined by synchrotron radiation (SR)-XRF imaging; and the valence change from the top to the base of roots was revealed for the first time by As K-edge XANES. Freeze-drying technique was adopted as an effective preparation method for the handling of roots. The vertical beam size was set to 300 µm by a spherical focusing mirror and the horizontal beam size was adjusted to 2800 µm by the slits. By adopting this wide X-ray beam, the elemental distribution along the roots can be appropriately evaluated despite their winding shapes. It was found that the concentration of arsenic became higher from the top to the base of the roots, while that of potassium remained almost constant. Furthermore, the oxidation state of arsenic at the top of the roots was dominantly As(III), while that at the base was As(V).
Keywords : SR-XRF imaging; As K-edge XANES; root; arsenic-hyperaccumulator fern; Pteris vittata L.
Kenji Kodama1 and Kazuaki Wagatsuma1
1 Institute for Materials Research, Tohoku University, 2-1-1, Katahira, Sendai-shi, Miyagi 980-8577(Received 9 March 2006, Accepted 6 June 2006)
A new three-electrode hollow cathode glow discharge lamp and a measuring technique were developed so that the sputtering process and emission process can be separated individually. The modulation technique was applied to the processes for creating a hollow cathode plasma as well as sputtering a sample. To detect specific emission lines of sample atoms from the overall signals, we used a Fast Fourier Transfer (FFT) spectrum analyzer. We could determine the bias voltages under the optimum discharge conditions for measuring the emission signal of the sample selectively by reading the component of the sputtering frequency in the FFT power spectrum. A three-electrode hollow cathode glow discharge lamp with an FFT spectrum analyzer is a promising analytical method for microanalysis.
Keywords : hollow cathode plasma; Fast Fourier Transfer spectrum analyzer; modulation technique; glow discharge; atomic emission spectrometry.
Takashi Yokoyama1, Keiko Murata1, Sakiko Mukai1, Keisuke Uomoto1, Toshihiro Itoh1, Miwa Shibata1 and Michio Zenki1
1 Department of Chemistry, Faculty of Science, Okayama University of Science, 1-1, Ridai-cho, Okayama-shi, Okayama 700-0005(Received 31 March 2006, Accepted 15 June 2006)
Pre-concentration methods of aluminum for flame atomic absorption spectrophotometry (FAAS) by solvent extraction and solid-phase extraction using 8-quinolinol (8-HQ) derivatives as a chelating reagent were investigated, where an organic solvent extracted or dissolved the aluminum with the chelating reagent was directly introduced into FAAS. In the case of the solid-phase extraction of aluminum with 0.29 g of a powdered solid of 8-HQ using 100 ml of sample water in the presence of 0.1 mol dm-3 sodium carbonate buffer at pH 9.0 for 90 min stirring, the highest apparent enrichment factor of the aluminum ion was 28, when the powdered solid 8-HQ extracted the aluminum was dissolved in 1 ml of nitrobenzene (NB). In the case of solvent extraction, the highest pre-concentration of the aluminum by the solvent extraction of 1000 ml of the sample water in the presence of 0.1 mol dm-3 sodium carbonate buffer at pH 9.0 with 2 mol dm-3 8-HQ in 3 ml NB for 70 min stirring was achieved. The enrichment factor and the detection limit (3σ) of the aluminum were 514 and 2.7 ng ml-1, respectively. The relative standard deviation for FAAS signals in this method was 8.5% (n=8) for 10 ng ml-1 aluminum. The high pre-concentration method of solvent extraction was applied to the determination of aluminum in river water and tap water, resulting in 10.9, 4.5, and 9.5 ng ml-1 for tap water and two river-water samples, respectively.
Keywords : aluminum; 8-quinolinol; pre-concentration; flame atomic absorption spectrophotometry; river water.
Yasuhiro Gou1
1 Kumamotoshi Environmental Research Institute, 404-1, Tokorojima, Ezumachi, Kumamoto-shi, Kumamoto 862-0946(Received 28 March 2006, Accepted 29 June 2006)
A spectrophotometric method for the determination of nitrate-nitrogen was developed based on the reaction of nitrate with 1-naphthol-8-sulfonic acid in the presence of sulfuric acid and chloride. A calibration curve based on the absorbance at 350 nm against a reagent-blank reference was linear in the concentration range of 0~6.00 µg/ml of nitrate-nitrogen. The color development can probably be ascribed to the formation of a nitroso-derivative of the parent acid caused by nitrosyl chloride resulting from the reaction of nitrate and chloride under strongly acidic conditions. The interference of common inorganic anions and cations was not serious, expect for nitrite, which gave a high positive error. This method was able to measure nitrate-nitrogen in well water and river water. The results were in good agreement with those obtained by an ion chromatographic method. In addition, this method gave satisfactory results in the determination of total nitrogen in sewage water, and was also useful for a semi-quantitative analysis of nitrate based on the strength of the developed color.
Keywords : nitrate; total nitrogen; 1-naphtol-8-sulfonic acid; spectrophotometry; nitrosil chloride.
Takakazu Hanzawa1, Kunio Nagashima1, Minori Kamaya1, Gaku Ishiguro2 and Nobuo Nakano2
1 Department of applied chemistry, Faculty of Engineering, Kogakuin University, 2665-1, Nakano-machi, Hachioji-shi, Tokyo 192-0015(Received 16 March 2006, Accepted 13 June 2006)
A sample solution was pumped at a flow rate of 3 ml min-1 to a transparent PTFE tube (3×2 mm, 170 cm length), which was wound around an UV lump (rod shape, 17 mmφ, 145 mm length, l=254 nm, 4 W). A metal cyano complex {potassium hexacyanoferrate(III) (0~0.2 mgCN dm-3)} was converted to CN- by UV (254 nm) irradiation of a sample solution at an efficiency of 100% (1 mol to 6 mol of CN-). Zn(II) and Cu(II)cyano complexes were successfully converted to CN- by the UV irradiation. The CN- produced was determined as follows. The sample solution was pumped to the mixing joint, where sulfuric acid (0.05 M) was mixed at a rate of 2 ml min-1. A mixture containing hydrogen cyanide was fed into a gas-liquid separation tube (pore size, 1 µm; microporous Teflon tube of 2 mm i.d., 3 mm o.d., 900 mm length). Hydrogen cyanide that evolved from the gas-liquid separation tube was purged by purified air (700 ml min-1) onto HCN monitoring tape. The efficiency {CN-→HCN(gas)} obtained by using the gas liquid separator was about 3%. When the monitoring tape was exposed to HCN gas, the tape became homogeneously colored. The degree of color intensity was proportional to the concentration of CN- in the sample solution. The relative standard deviation of the response to 0.1 mgCN- dm-3 was 2.1%. The method has detection limits of 0.02 mgCN dm-3 with a sampling time of 5 minutes. Standard addition method showed that this method could detect cyanide in a treated waste liquid of a chemical laboratory.
Keywords : determination of cyanide; decomposition by UV irradiation; transparent Teflon PFA tube; HCN gas monitoring tape; N,N-diethyl-p-phenylenediamine.
(Received 28 March 2006, Accepted 4 July 2006)
The flow injection analysis of a trace amount of chromium ion was investigated by an on-line concentration method using a Teflon filter tube. 1,5-Diphenylcarbazide was used as a detection reagent for the spectrophotometric determination of Cr(VI). Cr(VI) was coprecipitated with aluminum hydroxide in a reaction coil at pH 8.0~8.5; then, the coprecipitate of Cr(VI) and Al(III) was collected with a filter tube by concentration for 5 min at a sample flow rate of 2 ml/min. The precipitate collected was eluted with 1 M HNO3 as a carrier solution. The Cr(VI) was determined on-line by monitoring at 542 nm. When Al(III) was used as a precipitant, the limit of detection and the lower limit of determination for Cr(VI) were 0.08 and 0.25 ppb, respectively. The relative standard deviation (RSD) for 30 ppb Cr(VI) was 0.3% (n=7). On the other hand, Pb(II) was used as a precipitant; then, a calibration curve constructed by 60 min concentration for Cr(VI) was linear over the range 0 to 50 ppb. The limits of detection and determination for chromium were 0.004 and 0.013 ppb, respectively. The RSD for 2 ppb Cr(VI) was 1.0% (n=7). The proposed method was applied to the determination of river water samples. As a result, the chromium in the natural water samples examined was below the detection limit (0.004 ppb). The proposed FIA system could afford a simple and rapid analysis of Cr(VI) in natural water samples.
Keywords : on-line concentration; Teflon filter tube; spectrophotometric determination; chromium(VI); FIA.
Asako Akiyama1, Kaori Imai1, Sachiko Ishida1, Kenji Ito1, Tadashi Kobayashi1, Hideo Nakamura1, Kazutoshi Nose2 and Takao Tsuda3
1 Foods Laboratory, Kanebo Foods, LTD., 6-20-1, Kajihara, Takatuki-shi, Osaka 569-0091(Received 26 December 2005, Accepted 9 June 2006)
An analytical method for the determination of aromatic compounds exhalated from hand skin has been proposed. The sampling of exhalated aromatic compounds was performed as follows: after the intake of aromatic compounds included in chewing gum or a capsule, exhalated skin gas was collected from a hand. The hand was covered with a sampling bag of poly vinyl fluoride (PVF) for 30 min. Then, the inner space of the sampling bag was sprayed with a 25% of ethanol aqueous solution. After removing the hand from the bag, the trapped solution containing skin gas was collected. The aromatic compounds in the trapped solution were extracted to the solid phase as Twister® (stir bar coated with poly dimethyl siloxane, Gerstel). Extracts were determined by gas-chromatograph mass spectrometry using a thermo desorption system and a selective ion mode. Linalool, citronellol and geraniol, which are the main components of rose essential oil, were detected from the skin of a hand after an oral intake of rose oil. The exhalated absolute amount of linalool, citronellol and geraniol increased in 30 to 60 min, and then decreased after intake. The recoveries of linalool, citronellol and geraniol were 53.5%, 66.7% and 55.1%, respectively. The correlation coefficient of the standard curves for linalool, citronellol and geraniol were 0.9977, 0.9994 and 0.9987, respectively. Each compound exahalated from the skin of a human body during 6 hours after intake was estimated to be, according to the amount of intake, 0.39%, 0.09% and 0.25%, respectively, for one subject. The absolute amount of geraniol exhalated from a hand increased significantly after oral intake for 8 subjects (P<0.025). This is the first report to present hard proof that an aromatic compound was exhalated from human skin after its intake as food.
Keywords : geraniol; skin gas; GC/MS; solid-phase extraction; thermo-desorption system.
Seiichiro Ioka1, Teruki Iwatsuki1, Osamu Kato2 and Tsuyoshi Imakita3
1 Tono Geoscientific Research Unit, Geological Isolation Research and Development Directorate, Japan Atomic Energy Agency, 1-64, Yamanouchi, Akeyo-cho, Mizunami-shi, Gifu 509-6132(Received 1 May 2006, Accepted 11 July 2006)
A performance test for a redox potential measurement of a solution was conducted using continuously polished and untreated platinum working electrodes under an inert condition. The redox potential, measured by a polished electrode, immediately showed steady value which approximately coincided with the equilibrium value of redox reaction between HS- and S42-. Thus, the redox potentials could be controlled by the equilibrium of the redox reaction. On the other hand, the redox potential measured by an untreated electrode was +0.2 V higher than that measured by a continuously polished electrode. The measured redox potential implies that SO42- was the dominant species in the solution. A disagreement of the redox potentials measured by polished and untreated electrodes may have been caused by deactivation of the platinum electrode by the adsorption of sulfuric acid anions.
Keywords : solution; redox potential; platinum electrode; continuous polishing.
Kazuhiko Nakano1,2,3, Toshihiro Nakamura1,4, Izumi Nakai1,5, Akira Kawase1,6, Makoto Imai1,7, Mikio Hasegawa1,7, Yohichi Ishibashi1,8, Isamu Inamoto1,9, Kazuhuyu Sudou1,10, Masaru Kozaki1,11, Akira Turuta1,11, Akihiro Ono1, Kazutoshi Kakita1 and Mamoru Sakata1
1 The committee for the plastic CRMs for hazardous metals in The Japan Society for Analytical Chemistry, 1-26-2, Nishigotanda, Shinagawa-ku, Tokyo 141-0031(Received 25 January 2006, Accepted 2 June 2006)
The Japan Society for Analytical Chemistry has developed new plastic certified reference materials (CRMs) for the analysis of four hazardous elements (Pb, Cd Cr and Hg) in plastics to ensure the quality control of analyses. These CRMs (named as JSAC 0601-1 and 0602-1) were prepared by leading a raw material liquid of polyester resin mixed with hardener and organometallic compounds into a flat mold. The obtained plastics plates were crushed in a chip form by a mill, and sieved to obtain 0.5~1 mm size pieces. An interlaboratory comparison study was performed with the participation of 20 laboratories. z-scores of the robust method were applied for a statistical analysis. The certified uncertainties were determined at the confidence levels of 95%. These presented CRMs are the first reference materials for plastics in Japan for the analysis of hazardous metals contained in plastics, and are expected to be useful for the quality assurance and quality control of trace metals in plastics.
Keywords : plastics; certified reference materials; chip form; interlaboratory comparison study; hazardous elements (Pb, Cd, Cr, Hg).
Akira Nose
Suigei Brewing Co., Ltd., 566-1, Nagahama, Kochi-shi, Kochi 781-0270
(Awarded by Kochi University dated March 23, 2005)
The effects of solutes on the hydrogen-bonding structure of water-ethanol were investigated in water-ethanol solution on the basis of 1H NMR chemical shifts of the OH of water and ethanol. It was found that the hydrogen-bonding structure of water-ethanol is strengthened by acids or (poly)phenols. Not only acids (H+ and HA: undissociated acids) but also bases (OH-and A-: conjugate-base anions from weak acids) had the effect of strengthening the hydrogen-bonding structure of water-ethanol. Alcoholic beverage is a kind of water-ethanol solution containing flavor and taste. The properties of the hydrogen-bonding of water-ethanol in alcoholic beverages have not been revealed sufficiently. We investigated what could affect the hydrogen-bonding structure of water-ethanol in alcoholic beverages on the basis of 1H NMR chemical shifts and the Raman OH stretching spectra. It was also demonstrated that the hydrogen-bonding is strengthened by chemical components in real alcoholic beverages (whiskey, Japanese sake, shochu). It can be suggested that hydrogen-bonding donors as well as acceptors in alcohol beverages, which exist as the initial components or are gained later on, should cause a tight association between water and ethanol molecules.
(Received June 2, 2006)
Keywords : chemical shift in 1H NMR; hydrogen bonding; Raman spectrum; water structure; water-ethanol; alcoholic beverage; whiskey; Japanese sake; shochu.
Shinsuke Ohno
HME Co., Ltd., 17-1, Eba, Kuwana-shi, Mie 511-0836
(Awarded by Aichi Institute of Technology dated February 23, 2006)
At first, a copper- and/or iron-catalyzed coupling reaction of p-anisidine with N,N-dimethylaniline in the presence of hydrogen peroxide was investigated by batchwise and flow-based methods for the determination of copper and iron in natural water samples. The addition of some ligands (neocuproine for copper and 1,10-phenanthroline for iron) activated the catalytic effects. A flow injection (FI) method using catalytic reactions with a serial flow cell, having two cell compartments, was also applied to the successive assay of labile and inert complexes with humic acid for the characterization of copper and iron complexes. In addition, a sensitive and rapid FI spectrophotometric method was proposed for the determination of cobalt in cobalt alloy, pepperbush leaves and vitamin B12. It is based on a redox reaction of cobalt(II) with iron(III) in the presence of nitro-PAPS, producing a iron(II)-nitro-PAPS complex. Finally, a sequential injection (SI) method with a lab-on-valve (LOV) format using 5-Br-PSAA was developed for the simultaneous spectrophotometric determination of copper and iron. The computer-controlled SI-LOV system was useful for routine, durable and automated assays of copper and iron in industrial waste water samples. The flow-based analytical techniques with FIA and SI-LOV should be noticed as an environmentally benign technology.
(Received May 10, 2006)
Keywords : catalytic method; water-soluble chromogenic reagent; spectrophotometry; flow injection; sequential injection; simultaneous determination; iron; copper; cobalt.
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