Vol. 4 9, No. 2
February, 2000
Akiyo Yamauchi and Takashi Hayashita*
*Department of Chemistry, Graduate School of Science, Tohoku University, Aoba, Aramaki, Aoba-ku, Sendai 980-8578
(Received 10 November 1999)The recent developments of metal-ion probes based on photosignal transduction are reviewed in relation to their molecular design and response function. The metal-ion probes are classified into two types according to their design concepts: one is "molecular built-up" probes, in which ion recognition is performed by a single molecular receptor function; the other is "molecular assembled" probes, which are based on a supramolecular interaction derived from plural receptor molecules. For these probes, the principal mechanisms of photosignal transduction upon metal-ion recognition are summarized and their applications to metal ion sensing are discussed.
Keywords : metal-ion probe; photosignal transduction; fluoroionophore; chromoionophore; chemosensor; supramolecular chemistry.
Haizhou Wu*1, Noriyuki Watanabe*2, Ryoichi Tsukahara, Takao Itoh*3, Yohichi Gohshi*4 and Masanori Owari*5
*1 Institute of Industrial Science, the University of Tokyo, 7-22-1, Roppongi, Minato-ku, Tokyo 106-8558
*2 Department of Applied Chemistry, School of Engineering, the University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656
*3 Central Research Laboratory, Sumitomo Metal Mining Co., Ltd., 3-18-5, Nakakokubun, Ichikawa-shi, Chiba 272-8588
*4 National Institute for Environmental Studies, 16-2, Onogawa, Tsukuba-shi, Ibaraki 305-0053
*5 Environmental Science Center, the University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033
It is very difficult to accurately quantify trace rare-earth elements (REE) in ultra-pure rare-earth compounds by a single analysis method, such as ICP-AES, ICP-MS or electrothermal vaporization (ETV)/ICP-MS. We have developed a highly sensitive and efficient method by coupling the advantages of HPLC, ETV and ICP-MS. HPLC eliminated problems caused by matrix and severe overlapping of oxides and hydroxides peaks coming from the main component observed in ICP-MS. ETV greatly reduced the interference from additives contained in the eluent of HPLC, and provided an efficient introduction method for ICP-MS. The detection limits of other REE in pure Gd2O3 were 0.07~2 ng/g Gd. The method is applicable to analyses for 7~8 N pure metal and compounds.
Keywords : rare-earth; HPLC; electrothermal vaporization; ICP-MS; coupling technique.
Shang-Qian Wu, Tetsuya Kimishima, Hiroshi Masusaki*, Hiroaki Kuze and Nobuo Takeuchi**
*Tsukuba Laboratories, Nippon Sanso Corporation, 10, Ohkubo, Tsukuba-shi, Ibaraki 300-2611
**CEReS, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba-shi, Chiba 263-8522
(Received 22 September 1999, Accepted 8 November 1999)
The amount of trace moisture is precisely determined in N2 and HCl gases by means of near-infrared diode-laser absorption spectroscopy. As an optical source, we use a near-infrared InGaAsP distributed-feedback diode laser which operates at room temperature. A multi-pass sample cell designed for corrosive gases is employed to enhance molecular absorption. For the purpose of reducing the etalon noise that is usually encountered in multi-pass absorption spectroscopy, we adjust the base path length in accordance with the bandwidth of a molecular spectral line so that the etalon frequency does not critically overlap with that of the molecular spectrum. The remaining noise is further reduced by applying multi-stage smoothing. Trace moisture content as small as 2.3 ppb is detected with a 20-m absorption length.
Keywords : trace moisture; hydrogen chloride; diode-laser; near-infrared; absorption; multi-pass cell; gas impurity analysis.
Tetsuya Sato, Misa Kato, Katsunori Kimijima, Masaki Okuyama* and Kiyoshi Chiba**
*Faculty of Engineering, Saitama University, Urawa-shi, Saitama 338-8570
**Material Analysis Research Laboratories, Teijin Limited, Hino-shi, Tokyo 191-8512
A metastable transfer emission spectroscopy (MTES) combined with a tungsten coil atomizer was carried out for the sensitive determination of cadmium. Pulse atomization induced by a capacitor discharge to the coil atomizer produced a condensed vapour, which was transported and mixed with active nitrogen in a metastable state produced by a microwave discharge. A high sensitivity was obtained from the emission of cadmium by this system. Some new spectra were observed by MTES. Five ml of a cadmium solution acidified with nitric acid was deposited on the coil atomizer. A detection limit of less than 5 pg was obtained at a wavelength of 326.1 nm. This system is more sensitive by a factor of six than a system using a Ta boat. The linearity range of a calibration curve was from 5 to 200 pg Cd, beyond which the emission signal intensity was saturated. The saturation is likely to be controlled by the density of metastable nitrogen molecules existing in the excitation region.
Keywords : metastable transfer emission spectroscopy; active nitrogen; tungsten coil atomizer; cadmium.
Shan Ji, Tomoki Yabutani, Akihide Itoh, Koichi Chiba and Hiroki Haraguchi*
*Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603
(Received 20 September 1999, Accepted 23 November 1999)The distributions of major-to-ultratrace elements into natural salt from coastal seawater in a salt-preparation process were investigated by ICP-AES (inductively coupled plasma atomic emission spectrometry) and ICP-MS (inductively coupled plasma mass spectrometry) with preconcentration using a chelating resin. The coastal seawater samples were collected off-shore near to the Nie coast, where Agehama-made salt is produced by a classical Agehama method. Natural salt was produced from original coastal seawater in the laboratory in a similar manner to the Agehama method. First, the seawater samples were filtered with a membrane filter (pore size of 0.45 µm), and the elements in the dissolved fraction (filtrate) and in the particulate fraction (particulate on the filter) were determined by ICP-AES and ICP-MS. The analytical results for seawater indicate that alkali elements, alkaline earth elements, and oxoanion-forming elements (V, Mo, W, U) were dominantly in the dissolved fraction, while other elements such as Al, Fe, Pb and rare earth elements were mostly in the particulate fraction. The elements in laboratory-made salt and Agehama-made salt were also determined by ICP-AES and ICP-MS after dissolving them in a 0.1 M HNO3 solution. Although the concentrations of trace elements in laboratory-made salt and Agehama-made salt were almost at the same levels for 27 elements among 34 elements within a factor between ca. 1/5 and 5, Ba, Mn, Cd and Pb in Agehama-made salt were much higher (8-30 fold) in concentration than those in the laboratory-made salt. Based on the experimental results mentioned above, the distributions of major-to-ultratrace elements into natural salt from seawater were discussed, taking into consideration the preparation process of natural salt.
Keywords : natural salt; coastal seawater; major-to-ultratrace elements; ICP-AES; ICP-MS.
Michio Zenki, Yoshihiko Nakakita, Aika Komatsu and Takashi Yokoyama*
*Department of Chemistry, Faculty of Science, Okayama University of Science, 1-1, Ridai-cho, Okayama-shi, Okayama 700-0005
(Received 5 October 1999, Accepted 4 November 1999)The use of a closed-loop system in flow-injection analysis (FIA) allows for the recycling of reagents which are present in excess. Strong acids and bases are determined by injection into a continually circulated buffer solution containing an acid-base indicator. Neutralization occurs in the sample zone and discoloration of an indicator is monitored by spectrophotometry. Passing though the flow cell, the resulting solution is then buffered and returns to the reservoir. A typical aqueous reservoir solution contained 0.1 M acetate buffer and 1.5×10-4 M Methyl Orange. This solution was circulated at a flow rate of 2.5 ml/min. Sample (acid or base) aliquots of 2 µl were introduced into the stream and the differential absorbances were monitored at 530 nm. The calibration curve of samples by this method showed good linearity over a range of 0.1-5 M. Acids (HCl, HNO3, H2SO4, and oxalic acid) and bases (NaOH, KOH and NH3) gave the same slope of the calibration curve, respectively. Although a slight gradual increase in the baseline shift could not be avoided, it allowed 500 repetitive determinations of 1 M HCl or NaOH with the same 100 ml of circulating 0.1 M acetate buffer solution.
Keywords : closed-loop flow system; repetitive determination; spectrophotometry; strong acids and bases.
Tomokazu Tanaka, Kenji Furuhashi, Daisuke Matsuo and Masataka Hiraide*
*Department of Molecular Design and Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603
(Received 2 September 1999, Accepted 8 November 1999)A combined method of electrothermal vaporization and ICP-MS was studied for microtrace analysis. A 5 µl volume of a sample was placed on a tungsten filament (0.2 mm in diam.×45 mm) and desolvated electrothermally. Arsenic in the residue was then vaporized by increasing the temperature of the filament to 2450°C with the aid of a capacitor (0.22 F) and then carried in an argon stream to an ICP torch. The filament was used repeatedly at least 100 times. The relative standard deviation (n=10) for signal intensities of 15 pg As was ca. 10%, with an absolute detection limit (3σ) of 1 pg. The proposed method was applied to the determination of arsenic in a certified reference human hair sample. The analytical results obtained for the sample (decomposed with 14 M nitric acid and hydrogen peroxide) were 0.35±0.03 µg g-1, which almost coincided with the certified values (0.31±0.02 µg g-1).
Keywords : ICP-MS; electrothermal vaporization; arsenic; human hair; microtrace analysis.
Yoshio Machida
Analytical Chemistry Department, Product & Technology Development Laboratory, Tanabe Seiyaku Co., Ltd., 3-16-89, Kashima, Yodogawa-ku, Osaka 532-8505
(Awarded by Nagoya City University, dated October 5, 1998)Enantiomers often differ in pharmacological activity. Usually, only one of the various isomers fully contributes to therapeutic action, and the others do not. The separation of enantiomers is a subject of great interest because the antipode of a chiral drug is regarded as being an impurity from the viewpoint of quality control. Recently, chromatographic techniques, especially high-performance liquid chromatography with chiral stationary phases (CSPs), have been extensively used to achieve direct enantiomer separation. Various kinds of CSPs are commercially available. In this study, (1) the author designed and prepared novel CSPs (CSP-18C6I, II, III) which immobilized chiral crown ether ((+)-18-crown-6 tetracarboxylic acid). Then, the CSPs (18C6 series) were applied to the enantiomeric separation of amino acids, aminoalcohols and some hydrophobic amino compounds, which were them enantioseparated successfully. (2) Studies of the chiral-recognition mechanism of 18C6H4 using NMR and crystalline X-rays were performed and explained. (3) A modification (the addition of metal cations or cyclodextrin) of the mobile phase used in Crownpak CR(+), where hydrophobic chiral crown ether was dynamically coated on an ODS column, was investigated. A fast analysis of hydrophobic amino compounds was accomplished using this method.
(Received October 22, 1999)Keywords enantiomer separation; chiral crown ether; chiral stationary phase; HPLC; NMR; crystalline X-ray.
Yoshihiro Mori
Advanced Technology Research Laboratories, Nippon Steel Corporation, c/o NSC Electron Corporation, 3434, Shimata, Hikari-shi, Yamaguchi 743-0063
(Awarded by Kyushu University, March 25, 1999)Metallic impurities on the surface of semiconductor wafers deteriorate the electrical properties of LSI devices. In recent years, total reflection X-ray fluorescence (TXRF) spectrometry has come into wide use in semiconductor industry for the analysis of metal impurities. In TXRF analysis, the properties of a standard sample, especially the depth distribution of the analyte, are significant for accurate quantification. First, requirements for standard samples are discussed. Next, a study of metal adsorption in ammoniac hydrogen peroxide cleaning solution through equilibrium analysis is considered. It has been found that the properties of the wafers, on which metals are adsorbed in the solution, are suitable for standard samples of TXRF. This method was named "immersion in alkaline hydrogen peroxide (IAP)". The depth distribution of analyte on IAP wafers was evaluated by fitting angle scan data. After carrying out the above-mentioned studies, cross-check experiments between TXRF and other methods at a level of 1012 atoms cm-2 were conducted by using the IAP standard samples. The study clarified that the IAP standard samples are suitable for crosscheck experiments. Finally, the accuracy of TXRF below a level of 1011 atoms cm-2 was examined. With IAP standard samples, the determination values of TXRF agreed with those of AAS with an accuracy of 20%.
(Received October 22, 1999)Keywords total reflection x-ray fluorescence (TXRF); standard sample; semiconductor; silicon wafer; high accuracy analysis.
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