Vol. 47, No. 5
May 1998
Tatsuhiko Tanaka, Manabu Adachi, Takashi Ishiyama*, Maki Sato** and Akihiro Ono***
*Faculty of Engineering, Science University of Tokyo, 1-3, Kagurazaka, Shinjuku-ku, Tokyo 162-8601
**Advanced Materials & Technology Research Laboratories, Nippon Steel Corporation, 20-1, Shintomi, Futtu-shi, Chiba 293-0011
***Advanced Materials & Technology Research Laboratories, Nippon Steel Corporation, 3-35-1, Ida, Nakahara-ku, Kawasaki-shi, Kanagawa 211-0035
Differential pulse anodic stripping voltammetry with a rotating glassy carbon-disk electrode in an acidic solution without any separation of the matrix is described for the determination of copper at the µg g-1 level in iron and steel. The interference of iron(III) was eliminated by reducing it with l(+)-ascorbic acid to iron(II). The calibration curves were linear over a concentration range of 1.6×10-8 to 3.2×10-5 M of copper with pre-electrolysis times of 1200 to 5 s and passed through the origin (correlation coefficients >0.9992). The detection limit (3σ) was 0.78 ng ml-1 for a pre-electrolysis time of 1200 s. The possible interferences were evaluated. Compared with the present JIS methods, the developed method has been successfully applied to the determination of 0.5 to 1000 µg g-1 of copper in iron and steel without any troublesome preconcentration steps using harmful chemicals. The relative standard deviations were approximately 0.9% at the 10 µg g-1 level. The time required for an analysis was within 50 min.
Keywords: copper in iron and steel; anodic stripping voltammetry; steel analysis; glassy carbon electrode.
Masayuki Okamoto, Ryoko Yakawa, Masanobu Wakasa and Tatsushi Wakisaka*
*The Research Center for Characterization and Analytical Science, KAO Co., 1334, Minato, Wakayama 640-8580
(Received 2 October 1997, Accepted 12 March 1998)Numerous studies on surface functional-group analysis by X-ray photoelectron spectroscopy (XPS) preceded by chemical derivatization have been reported. In the present work we established a novel gas-phase chemical-derivatization technique for amine groups. Pentafluorobenzaldehyde (PFBA) has been reported to be a derivatization reagent for primary amine, but trifluoroaceticanhydride ( TFAA ) has been found to be more effective for the amine group. Although TFAA is known to react with primary and secondary amines and hydroxyl groups, we found that the hydroxyl group derivatized by TFAA could be cleaved by exposure to ammonia vapor; on the other hand, the amine group was not. According to this set of preparations, only the amine groups could be selectively modified, even if both the hydroxyl and amine groups existed on the surface. We concluded that this method is superior in chemical reactivity and selectivity for derivatization with PFBA; furthermore, it is available for derivatization of both the primary and secondary amine groups.
Keywords: XPS, functional group; polymer surface; selective chemical derivatization; hydroxyl group; amine group.
Masaaki Ishikawa*, Rieko Matsuda, Yuzuru Hayashi, Kumiko Sasaki and Masatake Toyoda**
*Numazu Health Center, 1-3, Takashima-honmachi, Numazu-shi, Shizuoka 410-0055
**National Institute of Health Sciences, 1-18-1, Kamiyoga, Setagaya-ku, Tokyo 158-8501
Five methods to estimate the detection limit were compared. Sorbic acid was analyzed by high-performance liquid chromatography (HPLC), and the detection limit was obtained by the following methods: (1) based on the 1/f fluctuation of the HPLC baseline, (2) based on the standard deviation of the measurement, (3) relative standard deviation of the measurements, (4) residual variance of the calibration line, and (5) baseline noise. These methods gave similar estimates of the detection limit. The standard deviation of the blank measurement was estimated by methods (1) to (4). Methods (2)〜(4) were used to estimate the standard deviation based on repetitive measurements. Method (1), however, was used to estimate the standard deviation without repetition, and gave a precise limit of detection (LOD) in the shortest measurement time.
Keywords: limit of detection (LOD); precision; HPLC.
Arkin Iburaim, Masayuki Itagaki and Kunihiro Watanabe*
*Department of Industrial Chemistry, Faculty of Science and Technology, Science University of Tokyo, 2641, Yamazaki, Noda-shi, Chiba 278-8510
(Received 16 January 1998, Accepted 24 March 1998)The on-line adsorption-concentration of a trace amount of Ce(III) onto a Teflon tube treated by an alkaline solution was investigated for flow-injection analysis (FIA). Several kinds of Teflon tubes were used, and the availability for adsorption was compared. By the fluorometric method with on-line adsorption, Ce(III) could be determined at the concentration range from 0.03 ppb to 10 ppb. The adsorption concentration showed a maximum at a pH between 7 and 10, indicating that the adsorbed species were hydroxide positively charged. 1.5 M HCl 58 µl was used for dissolution of adsorbed species in order to increase the detection intensity. It took two hours to determine 0.03 ppb of Ce(III). The amount of Ce(III) adsorption was 1.5 mg/m2 under the following conditions: inner diameter of Teflon tube, 0.5 mm; length of the Teflon tube, 3.0 m; 10 ppm Ce(III); pH 9.7; flow rate, 1.0 ml/min; period of concentration, 20 min.
Keywords: on-line adsorption concentration; Teflon tube; cerium(III); fluorometry; FIA.
Teruo Kitamura, Eiji Yoshimoto, Kiyoshi Watanabe* and Taketoshi Nakahara**
*Research & Development Dept., Showa Aluminum Corp., 6-224, Kaisan-cho, Sakai-shi, Osaka 590-8576
**Department of Applied Chemistry, College of Engineering, Osaka Prefecture University, 1-1, Gakuen-cho, Sakai-shi, Osaka 599-8531
The influence of moisture on the reliability of the determination of hydrogen in aluminium by the N2 carrier fusion method was studied. It was found that it is necessary to keep the water vapor in the hydrogen-extraction area at under 10 mg/m3 in order to lower the surface hydrogen to less than 0.01 ppm (the instrumental detection limit). The surface waters on an aluminium sample was `adsorbed' water liberated by heating at a temperatures lower than 473 K, and `combined' water by heating above 573 K, both of which produced surface hydrogen. The combined water produced surface water much more than the adsorbed one. Essentially, although it was difficult to eliminate the influence of surface hydrogen on the determination of hydrogen, the surface water could be reduced to 1 mg/m2 or below by machining the sample in the cylindrical form under an atmosphere (3000 mg H2O/m3) with a stream of nitrogen. As a result, the surface hydrogen could be decreased to 0.01 ppm or less. In real analyses, however, surface hydrogen could also be achieved to 0.01 ppm by machining the sample very carefully with an ethanol lubricant at room atmosphere. An analysis of commercial high-purity aluminium (JIS 1N99), showed an average concentration of 0.092 ppm hydrogen and a relative standard deviation of 6.0% (n=30).
Keywords: determination of hydrogen in aluminium; water vapor; surface hydrogen on aluminium; surface water on aluminium; nitrogen carrier fusion method.
Tatsuya Kitade, Natsuko Yagihara, Koji Kajimoto and Keisuke Kitamura*
*Kyoto Pharmaceutical University, 5, Nakauchi-cho, Misasagi, Yamashina-ku, Kyoto 607-8414
(Received 22 December 1997, Accepted 12 March 1998)An easy and sensitive method for the determination of serotonin (5-HT), tryptamine (Try) and gramine (Gra) was developed by using solid-substrate room-temperature phosphorimetry on a poly (vinyl alcohol) substrate. The method did not require a dry gas flush during the measurement of phosphorescence. The phosphorescence intensities of the compounds were enhanced by using a NaOH solution {water_ethanol, 50:50 (v/v)} as the solvent, and potassium iodide and sodium dodecyl sulfate as enhancers. The order of spotting phosphor and enhancers onto the substrate also affected the phosphorescence intensity. The analytical figures of merit for these three compounds were as follows. The linear dynamic ranges of 5-HT, Try and Gra were 5~500, 2.5~250 and 2.5~250 pmol/spot (5 µl), respectively. The correlation coefficients of the calibration curves were over 0.991 and the relative standard deviations at 50 pmol/spot (5 µl) varied from 5.0 to 6.5%, showing a good precision of the proposed method.
Keywords: serotonin; tryptamine; gramine; room-temperature phosphorimetry; poly (vinyl alcohol).
Susumu Shimoyama and Yasuko Noda*
*Color Material Research Laboratory, Den Material Co., LTD., 5396 Kamiogino, Atugi-shi, Kanagawa 243-0201
(Received 16 September 1997, Accepted 25 March 1998)The quencher is troublesome for identifying natural dyestuffs used for coloring cloth based on the three-dimensional fluorescence spectra. Therefore, the quenching effect of Fe(II) and Cu(II) ions on the fluorescence intensity of dyed cloth has been investigated. It was confirmed by the three-dimensional fluorescence spectrum that Fe(II) and Cu(II) ions had a high-quenching effect on coloring cloth dyed with a no-mordant dye from the Amur cork tree (A) as well as with mordant dyes from Madder (B), Sappan wood (C) and Eulalia (D). The fluorescence of cloth dyed with (B), (C) and (D) using an aluminium mordant was completely extinguished by Fe(II) and Cu(II) ions. The effect of these quenchers could be efficiently removed by immersing these samples in an aqueous solution of Al(III) ions. As a result, the fluorescence is re-emitted from the samples, and this treatment makes it possible to identify these dyestuffs.
Keywords: quenching; Fe(II) ion; Cu(II) ion; natural dyestuffs; three-dimensional fluorescence spectrum.
Keiji Gamoh* and Nakamichi Yamasaki**
*Faculty of Education, Kochi University, 2-5-1, Akebono-cho, Kochi 780-8520
**Research Laboratory of Hydrothermal Chemistry, Faculty of Science, Kochi University, 2-5-1, Akebono-cho, Kochi 780-8520
Hydrothermal hot-pressing environments could be simulated as possible environments for chemical evolution toward polymerization of amino acids because the environments could possess high-pressure and high-temperature conditions, resulting from the dynamics of plate tectonics. We attempted the dehydration condensation of amino acids under hydro-thermal hot-pressing environments. A solid mixture of the starting materials, amino acids and inorganic materials, was sealed without water in an autoclave tube, and then treated under hydrothermal hot-pressing conditions. The pressure was 58.6 MPa and the temperature increased by 10°C/min from room temperature to 270°C; the duration times were 12 and 36 h. After the reaction, the product was granulated and dispersed in water by ultrasonication, and them centrifuged. Dipeptides, such as Gly-Gly and Phe-Phe in the aqueous parts from the starting glycine and phenyalanine, respectively, in the presence of silica gel or sodium carbonate were identified by the HPLC and LC/MS-SIM method. Their yields were approximately from 1.2 to 1.9%. Furthermore, an analysis of the solid parts by FT-IR obviously showed the formation of peptide compounds on a solid surface. An elemental analysis of the same solid parts showed the formations of oligomers, such as dimer and trimer of the starting amino acids. Under these experimentals hydrothermal hot-pressing environments could be concidered to be ideal sites for the abiogenic dehydration condensation of amino acids. Also the coexistence of some inorganic materials would be essential for the dehydration polymerization of amino acids.
Keywords: hydrothermal hot-pressing; condensation of amino acids; chemical evolution; LC/MS with electrospray.