Vol. 50 No. 8
August, 2001
Kaoru Yamada, Yoshiaki Tanizawa, Takashi Ujiie* and Toshiyuki Hobo**
*Lion Corporation, 7-13-12, Hirai, Edogawa-ku, Tokyo 132-0035
**Department of Applied Chemistry, Graduate Course of Engineering, Tokyo Metropolitan University, 1-1, Minami-Ohsawa, Hachioji-shi, Tokyo 192-0397
On-line coupling of capillary electrophoresis with frit-fast atom bombardment mass spectrometry (CE/Frit-FAB-MS) using a liquid junction interface was developed. This system realized attraction control of the solution in a separation capillary by the high vacuum of MS and the post addition of the FAB matrix. When a 20 mM-phosphate buffer solution was used as the carrier electrolyte, this system worked well without stuffing up the capillary. When trialkylbenzylammonium chlorides were analyzed, the peak width in MS detection broadened in comparison with that in UV detection. This phenomenon was found to be caused by diffusion in a capillary which connected a liquid junction to MS. This system was applicable for the analysis of tetraalkylammonium compounds which have no ultraviolet absorption.
Keywords : HPLC; capillary electrophoresis; MS; frit-fast atom bombardment ionization; trialkylbenzylammonium chloride; tetraalkylammonium bromide.
Takashi Ishiyama, Takafumi Kobori and Tatsuhiko Tanaka*
*Faculty of Engineering, Science University of Tokyo, 1-3, Kagurazaka Shinjuku-ku, Tokyo 162-8601
(Received 27 April 2001, Accepted 22 June 2001)The commonly used methods for the determination of trace silicon exhibit poor sensitivity, although there is a strong need to develop a sensitive and simple method. A highly sensitive differential pulse adsorptive stripping voltammetry based on the electrochemical characteristics of β-silicododecamolybdate was devised for silicon determination. A complex of silicon(IV) with hexaammonium heptamolybdate, β-silicododecamolybdate, was adsorbed on a glassy carbon electrode at -1.1 V vs. Ag/AgCl for 10 min in a hydrochloric-nitric acids mixture solution containing acetone, and was ultimately reduced to molybdenum(IV) oxide. The deposits were then stripped by a positive-going scan to -0.2 V vs. Ag/AgCl at a rate of 50 mV s-1. A single well-defined peak was observed at around -0.7 V vs. Ag/AgCl in the stripping curves. The unreacted heptamolybdate was masked with sodium tartrate, which acted as a masking agent of matrix iron(III). The calibration curve (peak area vs. concentration) was linear over the 0.5 to 100 ngSi(IV) cm-3 (1.8×10-8~3.6×10-6 mol dm-3) concentration ranges, with a sensitivity of 0.21 µA·V(ng cm-3)-1. The detection limit (3σ) was 4.3×10-9 mol dm-3. The proposed method was applied to the direct determination of 0.87 massppm of silicon in high-purity iron with an RSD of ca. 6%; its lower limit of determination was two orders of magnitude better than that of the current JIS method for chemical analysis. The time required for the whole procedure was within 80 min. No interference resulted from the foreign elements, which could form heteropoly acids with heptamolybdate.
Keywords : determination of silicon; stripping voltammetry; glassy carbon electrode; b-silicododecamolybdate; steel analysis.
Hitoshi Murayama, Hiroyuki Mukai, Akiko Tanabe, Noboru Moriyama* and Yoshie Kitayama**
*Niigata Prefectural Institute of Public Health and Environmental Sciences, 314-1, Sowa, Niigata 950-2144
**Department of Chemistry and Chemical Engineering, Faculty of Engineering, Niigata University, 8050, Igarashi2nocho, Niigata 950-2181
Applications of a high-resolution gas chromatograph/high-resolution mass spectrometer (HRGC/HRMS) have been examined with regard to the precise determination of various kinds of pesticides in air to low concentrations. The results for a comparison of the resolution of mass spectrometry indicated that the signal-noise ratio for pesticides in the standard solution improved for 21 of 28 kinds of pesticides at high resolution (R=5000). In addition, interfering substances readily influence the chromatograms of actual samples, though these substances were excluded from almost all of the pesticides due to improved resolution. This HRGC/HRMS method allowed an actual determination of pesticides in air. The collection of 10 m3 of air was performed with activated carbon tube collection. Following extraction, fractionation was performed with a florisil column. Sensitive and selective determinations to the order of 10-3 µg/m3 proved to be possible with respect to samples concentrated to 1 ml.
Keywords : high-resolution gas chromatograph/high-resolution mass spectrometer; pesticides; air; determination.
Mitsuru Hoshino, Itsuo Mori, Miho Motomatsu, Kenzou Nakatani, Takako Yamaguchi and Yoshikazu Fujita*
*Osaka University of Pharmaceutical Sciences, 4-20-1, Nasahara, Takatsuki-shi, Osaka 569-1094
(Received May 7, 2001, Accepted 2 June 2001)A spectrophotometric method for the determination of minocycline hydrochloride (MC) was established with p-carboxyphenylfluorone (PCPF) and titanium(IV). Beer's law was obeyed in a concentration range 5~25 µg of MC in 10 ml of final solution. The apparent molar absoptivity of the proposed method, which does not require an extraction procedure, is 1.2×105 l mol-1 cm-1 at 580 nm. The relative standard deviation for five replicate determinations for 12.3 µg of MC was 2.1%. The proposed method was then applied to the assays of MC in pharmaceutical preparation (tablet), and the results were satisfactory.
Keywords : minocycline hydrochloride; p-carboxyphenylfluorone; titanium(IV); spectrophotometry; in pharmaceutical preparation.
Ryuichi Yoshida, Chieko Kanno, Shinya Saito and Chikakiyo Nagata*
*Department of Applied Chemistry, Faculty of Engineering, Shibaura Institute of Technology, 3-9-14, Shibaura, Minato-ku, Tokyo 108-8548
(Received 22 March 2001, Accepted 5 June 2001)The 1H- and 13C-NMR spectra of the trimethyl(1-indenyl)carbon(IV) compound were measured. Assignments of the chemical shifts for 1H and 13C in this compound were obtained by means of hydrogen-hydrogen nuclear Overhauser effect spectroscopy (H-H NOESY), hydrogen-hydrogen correlation spectroscopy (H-H COSY) and carbon-hydrogen correlation spectroscopy (C-H COSY). The 13C chemical shifts of the methyl and C1 carbons were correlated with the electronegativity of the central elements: C, Si, Ge and Sn, of the (CH3)3C(C9H7), (CH3)3Si(C9H7), (CH3)3Ge(C9H7) and (n-C4H9)3Sn(C9H7) compounds.
Keywords : trimethyl(1-indenyl) compounds; 1H- and 13C-NMR chemical shifts.
Tatsuhiko Tanaka and Masaru Ishii*
*Faculty of Engineering, Science University of Tokyo, 1-3, Kagurazaka, Shinjuku-ku, Tokyo 162-8601
(Received 15 May 2001, Accepted 21 June 2001)A simple and highly sensitive method is described for the determination of copper in iron and steel based on differential pulse anodic stripping voltammetry using an iron(III) excluding technique by means of 4-methyl-2-pentanone (MIBK) extraction. A 3 cm3 aliquot of an acidic sample solution (4 mol dm-3 hydrochloric acid-0.5 mol dm-3 nitric acid) saturated with sodium chloride and 8 cm3 of the MIBK were transferred into an electrochemical cell, and iron(III) was extracted above 99.95% into MIBK phase after vigorous stirring for 1 min. Electrodes were inserted in the aqueous phase (bottom) without excluding the MIBK phase from the cell. Copper(II) remaining in the aqueous phase was electrodeposited on a rotating glassy carbon electrode at -0.8 V vs. Ag/AgCl for 5 min; the deposit was then anodically stripped at a scan rate of 50 mV s-1 to 0 V vs. Ag/AgCl. The calibration graph was linear over a concentration range (7.9~78.7)×10-7 mol dm-3 of copper(II) and passed through the origin. The detection limit (3σ) was 4.7×10-8 mol dm-3. The determination of 1.62 to 138 µg g-1 of copper in iron and steel was achieved with good precision and accuracy within ca. 50 min. The possible interferences have been evaluated. The proposed method is applicable to the determination of copper(II) down to 1.3 µg g-1 in 40 mg cm-3 of iron(III) for a deposition time of 5 min.
Keywords : copper; iron and steel; differential pulse anodic stripping voltammetry; MIBK extraction.
Takako Yamaguchi, Hironari Murase, Itsuo Mori and Yoshikazu Fujita*
*Osaka University of Pharmaceutical Sciences, 4-20-1, Nasahara, Takatsuki, Osaka 569-1094
(Received 17 May 2001, Accepted 29 June 2001)A spectrophotometric method for the determination of propranolol hydrochloride(PP) was established by using the Bromopyrogallol Red(BPR)-molybdenum(VI) complex. This method can be used to determine 1.5~30 µg/10 ml PP; the apparent molor absorptivity is 7.8×104 l mol-1 cm-1 at 618 nm. The proposed method was applied to assays of PP in pharmaceutical preparations (tablet, extend-release capsule and injection). Moreover, this method could be applied to the assay of drugs, such as chlorpromazine and alprenolol. The analytical results and recoveries were satisfactory.
Keywords : propranolol hydrochloride; spectrophotometry; Bromopyrogallol Red-molybdenum(VI) complex; pharmaceutical preparation.
Mitsuo Yamamoto and Takaharu Honjo*
*Department of Chemistry, Faculty of Science, Kanazawa University, Kakuma-machi, Kanazawa-shi, Ishikawa 920-1192
(Received 24 May 2001, Accepted 29 June 2001)A new method for the separation of chromium(VI) and chromium(III) with dicyclohexyl 18-crown-6 (DC18C6) in 1,2-dichloroethane was developed by means of solvent extraction. In this process, CrVI as HCrO4- was extracted as an ion-pair complex with the potassium-crown ether complex cation in the organic phase within 1 min. The extracted species was ascertained to be [K(DC18C6)]+·[HCrO4]-. When mixtures of CrVI and CrIII were extracted under the optimum condition, CrVI alone was extracted quantatively, whereas CrIII remained in the aqueous phase. After extraction, CrVI in the organic phase was quantatively back-extracted by a 0.1 M NH3 solution. Then, each of the concentrations of CrVI and CrIII could be determined by means of inductively coupled plasma atomic emission spectromrtry (ICP-AES). Cations, such as iron(III), zinc(II) and cadmium(II), interfered with this extraction. The present method was applied to recover CrVI trace in the presence of CrIII in real samples, and clarified to be applicable to CrVI determination in natural water samples.
Keywords : chromium(VI); chromium(III); dicyclohexyl-18-crown-6; ion-pair extraction; separation.
Yoshio Iida, Hiroyuki Igaki, Kouichi Tanaka, Syouzou Asada, Yohichi Ishibashi, Kazutoshi Kakita, Akira Turuta, Mamoru Sakata and Akihiro Ono*
*The Japan Society for Analytical Chemistry, 1-26-2, Nishigotanda, Shinagawa-ku, Tokyo 141-0031
(Received 9 April 2001, Accepted 22 June 2001)The Japan Society for Analytical Chemistry decided to issue a new certified reference material(CRM) for dioxins and a team has been organized to prepare a fly-ash material and to certify the concentration of dioxns in it. Round robin test was performed by 19 laboratories' participants. Robust-z-score method was applied to statistical analysis. The Presented CRM is the first composite standard materials of dioxins prepared in Japan and is expected to be useful for the quality assurance and quality control of dioxins analysis.
Keywords : fly-ash; dioxin analysis; certified reference material.
Kenji Kurihara, Fumiyo Tsuchiya and Tadao Shoji*
*Analysis Center, Dainippon Ink & Chemicals, Inc., 631, Sakado, Sakura-shi, Chiba 285-8668
(Received 2 April 2001, Accepted 3 July 2001)Keywords : GC/MS; high-frequency heating; polyamide; polyimide; methanolysis..
Hideaki Nakamura
Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904
(Awarded by The University of Tokyo dated December 11, 1998)Biosensors are expected to be simple, rapid, highly selective, and ecologically sound methods. We previously developed several phosphate ion (Pi) biosensors, the latest of which was a chemiluminescent-flow injection analysis (CL-FIA) system; however, its sensitivity and stability were not sufficient. As a result, it was found that, to implement our Pi biosensor, four conditions were required. These four conditions were: to achieve stability with high sensitivity (0.32 µM Pi; maximal permissible concentration in Japan); to establish a removal method of dissolved substances; to measure real samples; and to produce a complete automated biosensor system satisfying the above three requirements. To satisfy all requirements, we chose a biosensor using pyruvate oxidase G (from Aerococcus viridans) in three newly developed biosensors, and the biosensor was fitted compactly into a trial automatic CL-FIA system of the desktop type. After optimization, this system could detect 96-nM to 32-µM Pi (within 30 s) with an RSD of 2.3% (n=5) at 25±0.1°C and make the calibration curves (0.16-µM to 32-µM Pi, r=1.00) for at least two weeks. Treatment with activated carbon could improve the sensor response when inhibited by dissolved substances in fleshwater. The results, determined Pi concentrartions in real samples, obtained by the sensor system and the modified molybdenum blue method were compared, and good correlation (r=0.94, n=7) was obtained between them. (Received May 15, 2001)
Keywords : biosensor; phosphate ion determination; pyruvate oxidase; automatic CL-FIA system; freshwater.
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