Vol. 47, No. 10
October, 1998
Sadao Mori**
**Department of Industrial Chemistry, Faculty of Engineering, Mie University, Tsu-shi, Mie 514-8507
(Received 27 April 1998, Accepted 25 May 1998)The most important items in polymer analysis are the molecular weight {and molecular-weight distribution (MWD)} and the chemical composition {and chemical-composition distribution (CCD)}. High-performance liquid chromatography (HPLC) can be used to determine these items. Size exclusion chromatography (SEC) is used to measure the molecular weight and MWD. In order to obtain accurate and precise values of these parameters, problems associated with a calibration curve, abscissa (retention volume) and ordinate (detector response) must be carefully considered. Especially, since the fluctuation of abscissa by secondary effects for polar and ionic polymers is considerably large, it is required to clarify the relationship between the molecular weight and the molecular size by using a light-scattering detector. Round-robin tests can be used to clarify several problems associated with precise and accurate measurements of the molecular weight and MWD of nonpolar polymers. Non-exclusion liquid chromatography (NELC) for polymer separation can be divided into five separation techniques: adsorption, precipitation (solubility), normal and reversed phases, orthogonal, and adsorption at a critical point. These separation techniques are reviwed, especially the liquid adsorption chromatographic method developed at our laboratory is explained in detail. The measurement of MWD and CCD by the combination of SEC and NELC is also discussed. The future prospects of polymer analysis by SEC and NELC are also considered.
Keywords: size exclusion chromatography (SEC); non-exclusion liquid chromatography; molecular weight and molecular-weight distribution; chemical composition and chemical-composition disribution; round-robin tests.
Minemasa Hida and Toshiyuki Mitsui**
**Criminal Investigation Laboratory, Aichi Prefecture Police H.Q., 2-1-1, Sannomaru, Naka-ku, Nagoya 460-8502
(Received 13 March 1998, Accepted 15 April 1998)In this study a multivariate analysis was applied to forensic science samples for both the evaluation of similarity and a quantitative analysis. As for the evaluation of similarity, a classification of counterfeit coins by a cluster analysis using the analytical results of a fluorescence X-ray analysis is described. The determination of carboxyhemoglobin in human blood samples by a principal component analysis using visible absorption photometry is described as an example of quantitative analysis.
Keywords: forensic science sample; multivariate analysis; counterfeit coins; carboxyhemoglobin; cluster analysis; principal component analysis.
Akio Yuchi****Department of Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555
(Received 27 April 1998, Accepted 1 June 1998)Systematic equilibrium studies were carried out on the formation of mixed-ligand complexes with multidentate ligands and halides. Based on the obtained results, the separation and detection of anions were examined with new receptors containing Lewis-acidic centers: elucidation of the reactions used for colorimetry and fluorometry of fluoride and developement of new reaction systems; elucidation of the effects of anions on the extraction of metal ions and on their adsorption to chelating resins; the application of polymer complexes of Zr(IV) as an adsorbent for fluoride and as a stationary phase for immobilized metal affinity chromatography; the establishment of criteria for selecting the masking reagent in the potentiometric determination of fluoride.
Keywords: anion receptor; mixed-ligand complexes; separation of anions; detection of anions; immobilized metal affinity chromatography; adsorbent.
Ji-Ye Jin and Tomoo Miwa**
**Department of Chemistry, Faculty of Engineering, Gifu University, 1-1, Yanagido, Gifu 501-1193
(Received 6 May 1998, Accepted 4 June 1998)The electrochemical behavior of a Ni-Ti alloy electrode and its application to the amperometric detection of sugars in liquid chromatography are described. In strong basic media, the redox waves of Ni(III)/Ni(II) were observed at a Ni-Ti alloy electrode near to+0.5 and+0.45 V vs. Ag/AgCl, which is very similar to that on a Ni metal electrode. However, from the results of the time dependence in voltammetric measurements, the interconversion of oxide phase (from the α-Ni(OH)2 to β-Ni(OH)2) was found to be difficult on the Ni-Ti surface. An oxide film on the Ni-Ti electrode surface shows a high catalytic activity for the electrochemical oxidation of sugars. It is thus suggested that Ti in a Ni-Ti alloy stabilized the oxide structure while allowing the electrode to retain the catalytic activity of Ni. Ni-Ti electrode was applied as an electrochemical detector in liquid chromatography for the analysis of sugars. At an applied potential of+0.55 V vs. Ag/AgCl, the linear responses of sugars on the Ni-Ti electrode were found in the range from 0.5 to~500 µM. For a 10.2 µl sample loop, the detection limits (S/N ≥ 3) were 0.18 ng (0.1 µM), 0.36 ng (0.2 µM), 2.1 ng (0.6 µM), 2.6 ng (0.7 µM) and 2.2 ng (0.6 µM) for glucose, fructose sucrose, lactose and maltose, respectively. Since the Ni-Ti alloy electrode exhibited the excellent long-term stability as compared with other metallic electrodes, it has been confirmed to be a good electrode material for the electrochemical detection of sugars.
Keywords: Ni-Ti alloy electrode; corrosion resistance; catalytic oxidation of sugars; amperometric detection; liquid chromatography.
Yasuyuki Ishida, Hajime Ohtani and Shin Tsuge**
**Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603
(Received 6 May 1998, Accepted 10 June 1998)In this paper, some features of reactive pyrolysis-gas chromatography (reactive Py-GC) in the presence of various chemical reagents, such as an organic alkali or solid acid, are first presented. Then, typical applications of the reactive Py-GC to compositional analysis and a microstructural characterization of various synthetic high-polymers and natural organic compounds are overviewed. These applications include; 1) the determination of end groups and the chemical composition of polycarbonates; 2) the determination of cationic comonomers in polyacrylamide resins; 3) a study of the degradation mechanism of fully aromatic polyesters during reactive pyrolysis in the presence of an organic alkali; 4) the determination of rosin sizing agents in paper; 5) the determination of lipid components contained in a single zooplanter individual; and 6) the evaluation of sequence distributions of thermally stabilized polyacetals. All of these applications made significant contributions to opening up new practical methods to characterize the chemical composition and microstructure of engineering plastics and natural organic compounds to which conventional analytical methods often encountered various difficulties: 1) insufficient sensitivity for a trace amount of available samples weighing on the µg order, 2) the requirement of time-consuming, and loss and/or contamination-causing pretreatment of samples, and/or 3) insufficient solubility of samples in most solvents for spectroscopic measurements. Furthermore, the future scope of reactive Py-GC is brieflly discussed.
Keywords: reactive pyrolysis-gas chromatography; organic alkali; solid acid; compositional analysis; microstructural characterization; engineering plastic; natural organic compound.
Shinkichi Yamada**
**Faculty of Engineering, Shizuoka University, 3-5-1, Johoku, Hamamastu-shi, Shizuoka 432-8561
(Received 30 April 1998, Accepted 14 July 1998)From a mechanistic consideration of the reactivity of a metal ion and its complex, we have proposed equations to predict the rate constants for complex formation and ligand-substitution reactions, as well as the catalytic effect of a third ligand on a ligand-substitution reaction. Using these equations and the parameters involved in these equations, we have designed differential kinetic methods for determining inorganic species in different oxidation states. These include (1) the simultaneous determination of antimony(III) and antimony(V) based on the difference in rates for complexation with 3-hydroxy-7-methoxyflavone, (2) the selective determination of antimony(V) in the presence of antimony(III) based on the difference in rates for the ligand substitution of the 3-hydroxy-7-methoxyflavone complex with citrate, (3) the selective determination of tin(IV) in the presence of tin(II) based on the difference in rates for the complexation with morin, and (4) the selective determination of thiosulfate and sulfite in the presence of sulfate based on the difference in rates for the catalytic effect on the ligand substitution of mercury(II)-PAR complex with CyDTA.
Keywords: differential kinetic method of analysis; determination of antimony; determination of tin; determination of oxy-anions of sulfur.
Haruo Tsuji, Shinjiro Fujiwara, Kenji Chayama*, Kiyoshi Teranishi and Kimio Isomura**
*Konan University, 8-9-1, Okamoto, Higashinada-ku, Kobe-shi, Hyogo 658-8501
**The Hyogo Prefectural Institute of Public Health, 2-1, Arata-cho, Hyogo-ku, Kobe-shi, Hyogo 652-0032
ICP-MS was applied to the determination of rare-earth elements(REE) in Arima spring water. For the preconcentration of REE from matrix elements, an ion-exchange method using a chelating resin having an iminodiacetic acid functional group was applied. The analytical procedured was as follows: the dissolved iron in the sample, which forms hydroxide precipitates by pH adjustment and intefer the analysis of REE, was oxidized by HNO3 and then removed by an anion-exchange resin as a chloride complex under 4 M HCl acidity. The solution was adjusted to have a pH value of 5.5 with an acetate buffer and an ammonia solution, and was then stirred for 2 h after the addition of a chelating resin. The resin was collected by a glass filter and washed with a magnesium chloride solution, an ammonium acetate buffer solution and water to remove any alkali earth elements (Ca, Mg, Ba). REE adsorbed on the resin was eluted with 5 ml of 2 M HNO3. The Cd as an internal standard element was added to the eluent and diluted to 20 ml for determination by ICP-MS. The recovery of each REE was more than 90%. The total REE concentration and Eu anomalies of Na-Cl-Fe high-temperature spring water differed from Na-Cl-HCO3 low-temperature spring water in Arima.
Keywords: rare-earth elements; chelating resin; preconcentration; Arima spring water; ICP-MS.
Tomohiro Narukawa, Wataru Yoshimura and Atsushi Uzawa*
*Department of Chemistry, Chiba Institute of Technology, 2-1-1, Shibazono, Narashino-shi, Chiba 275-0023
(Received 15 April 1998, Accepted 13 July 1998)A simple method for the concentration and determination of lead and bismuth in environmental samples using a cobalt(III) oxide powder is described. It has been found that cobalt(III) oxide powder is applicable to the collection of lead and bismuth over the range of pH 1.0 to 11.0; also, its effectiveness as a chemical modifier for the determination of lead and bismuth by AAS using a tungsten furnace has been confirmed. Thus, cobalt(III) oxide has proven that it is an effective collector and chemical modifier for trace amounts of lead and bismuth. The analytical procedure is as follows. To a sample solution (pH 3.0) containing less than 0.5 µg of lead and 2.0 µg of bismuth, 30 mg of cobalt(III) oxide powder is added, and the mixture is stirred for 15 min by sonication. The mixture is separated to a cobalt(III) oxide powder and a liquid phase through a membrane filter by vacuum filtration. The cobalt(III) oxide powder on the filter is washed with water and the powder is dispersed in 5 ml of water by mixing with shaking. A 10 µl aliquot of the slurry is injected into a tungsten furnace, followed by heating at an ashing temperature of 1000°C (Pb) or 600°C (Bi) for 15 s. The absorbances of lead and bismuth were then measured at an atomization temperature of 2400°C for 2 s. The detection limits (3σ) of lead and bismuth were 7 ppb (0.07 ng/10 µl). The proposed method has been applied to geochemical standard rock and pond sediment samples.
Keywords: AAS using a tungsten furnace; determination of lead and bismuth; cobalt(III) oxide powder; geochemical standard rock and pond sediment samples.
Masaharu Komatsu, Tadashi Kubo, Taku Matsuo and Sunao Yamada*
*Department of Materials Physics and Chemistry, Kyushu University, 6-10-1, Hakozaki, Higashi-ku, Fukuoka 812-8581
(Received 29 May 1998, Accepted 13 July 1998)A thin poly(methyl methacrylate) (PMMA) film incorporating a hydrophobic viologen was prepared on a water surface. The film thickness was about 60 nm. Cyclic voltammetric measurements of the film were carried out by putting the film on the surface of an ITO electrode. Clear one-electron redox couples due to one- and two-electron reduction of the viologen were observed. The relationship between the peak current and the scan rate indicated that the viologen was confined to be inside the film. Two sheets of the films were put on the surfaces of a glass substrate; this film assembly was then immersed into an aqueous solution containing Ru(bpy)32+ and a sacrificial reagent. Visible-light illumination of the film assembly resulted in the appearance of characteristic absorption bands due to one-electron reduced viologen. From a comparison with luminescence quenching experiments of Ru(bpy)32+ in solution , the interfacial electron-transfer between the photoexcited Ru(bpy)32+ and the viologen was verified. The results demonstrate a redox-active thin PMMA film.
Keywords: viologen; thin PMMA film; electrochemical redox reaction; photochemical redox reaction.
Fumiaki Yokota, Tatsuo Nakano*, Toshio Ishizuka** and Hisashi Morikawa***
*Material Department, Industrial Research Institute, Aichi Prefectural Government, Nishi-Shinwari, Hitotsugi-cho, Kariya-shi, Aichi 448-0003
**Faculty of Science, Niigata University, 8050, Ikarashi 2, Niigata-shi, Niigata 950-2181
***Chemistry Department, National Industrial Research Institute of Nagoya, 1-1, Hirate-cho, Kita-ku, Nagoya-shi, Aichi 462-8510
In order to determine impurities (twelve elements) in vanadium nitride (VN) by inductively coupled plasma atomic-emission spectrometry (ICP-AES), a sample dissolution procedure using acids was examined. After a 0.25 g amount of VN powder sample was taken in a Teflon pressure vessel, 2 ml of nitric acid (1+1) and 2 ml of hydrofluoric acid (1+1) were added. The vessel was sealed and kept at 160°C in a drying oven. After 16 hours, the vessel was taken out from the oven and was then shaken two or three times in order to mix the contents. The vessel was again placed in the oven for 3 hours. When a small amount of free carbon, which existed in the sample, remained as a residue in the decomposed sample solution, the mixture was filtered so as to remove it. The filtrate or decomposed sample solution was transferred to a 100 ml calibrated flask with 20 ml of 4% boric acid, and then diluted with nitric acid (1+30). Twelve elements (Al, Ba, Ca, Co, Cr, Fe, Mn, Nb, Ni, Si, Ti and Zr) were determined by ICP-AES. The matrix effects on the background levels and the emission intensities of the elements were compensated by using matrix-matched standard solutions for a calibration. Twelve elements in commercial VN powder samples were determined with good precision. For most elements, the values obtained by the proposed method were found to be in good agreement with those obtained by atomic-absorption spectrometry. The recoveries from the sample to which twelve elements were spiked were 96% for Nb to 106% for Ni and Fe, and the detection limits were 0.14 µg g-1 for Ca to 10 µg g-1 for Si.
Keywords: ICP-AES; impurity determination; vanadium nitride; advanced ceramic; acid decomposition under high pressure.
Kei Toda*, Hiroshi Inoue* and Isao Sanemasa*
*Department of Environmental Science, Faculty of Science, Kumamoto University, 2-39-1, Kurokami Kumamoto 860-8555
(Received 20 April 1998, Accepted 1 July 1998)A miniaturized detector based on absorbing conductometry was constructed in order to measure the SO2 concentration in air. This detector is not only small, but is also capable of continuous measurement of SO2, unlike the conventional detectors for intermittent SO2 measurements. Two bilateral pairs of Pt electrodes were fabricated on a glass-epoxy substrate through conventional photolithography and sputtering. On this substrate, a cavity for the flow of an absorbing solution was formed with a Teflon sheet and a gas-permeable membrane. The absorbing solution, H2SO4-H2O2, was made to flow through this cavity of 2 mm in width and 0.5 mm in thickness by applying pressure to a reservoir of the solution. The sample gas was introduced into the other side of the membrane. Gaseous SO2 permeated through the membrane and dissolved into the absorbing solution, resulting in an increase in the electrical conductivity of the solution. Any change in the conductivity was monitored using Pt electrodes located both up- and downstream of the absorbing zone, and thus the SO2 concentrations were determined. The sensitivity and response time largely depended on the flow rate of the absorbing solution. Since the standard flow rate employed was 20 µl min-1, the volume of the waste solution, even over long-time operation, was sufficiently small to be carried. When the absorbing solution was flowed at this rate, from 10 ppb to 1 ppm of SO2 could be measured and the change ratio in the conductivity was 0.971 ppm-1. The response time (T90%) was 82 sec under the same conditions. Other gases interfered slightly; e.g. the sensitivity to CO2 was about 1/30000 of that of SO2, so the selectivity of this method was sufficiently good for facile use. This study furnished a step for constructing a miniaturized total chemical analysis system (µTAS) for SO2 measurements.
Keywords: detector of sulfur dioxide; flow absorbing solution; conductometry.
Kimitoshi Sato and Takashi Goto*
*Department of Industrial Chemistry, College of Engineering, Nihon University, 1, Nakagawara, Tokusada, Tamura, Koriyama-shi, Fukushima 963-8642 (Received 27 February 1998, Accepted 10 June 1998)The separation and preconcentration of trace nickel(II) and cobalt(II) form an aqueous solution for a graphite-furnace atomic-absorption spectrometric (GF-AAS) determination was studied using silica gel loaded with 4-(2-Pyridylazo)-resorcinol (PAR)/trioctylmethylammonium chloride (Capriquat). The proposed adsorbent was prepared as follows: ten grams of silica gel were shaken into 25 ml of a 5% Capriquat_xylen solution and a 0.01% PAR solution for 30 minutes. A sample solution of 100~1000 ml containing Ni(II) and Co(II) was adjusted to pH 9.0. The solution was then passed through 1.0 g of PAR/Capriquat-loaded in a silica gel column at a flow rate of 10 ml min-1. The Ni(II) and Co(II) collected on the PAR/ Capriquat-loaded silica gel on the column was eluted with 10 ml of 0.2 M nitric acid, and then deteminated by GF-AAS. In this method, over 99% of the Ni(II) and Co(II) was adsorbed at about pH 9.0. The calibration curve was linear from 0.05 to 2.5 µg/l Ni(II) and 0.03 to 3.0 µg/l Co(II). The proposed method has been applied to the determination of Ni(II) and Co(II) in sea-water samples.
Keywords : nickel(II) and cobalt(II); PAR/Capriquat loaded silica gel; graphite furnace AAS; seawater.
Shin-ichi Izumoto and Hiroyuki Nishi*
*Analytical Research Laboratory, Tanabe Seiyaku Co., Ltd, 3-16-89, Kashima, Yodogawa-ku, Osaka 532-8505
(Received 18 May 1998, Accepted 22 July 1998)Electrokinetic chromatography (EKC), which belongs to one branch of capillary electrophoretic (CE) techniques, enables the separation of electrically neutral compounds by the CE technique through a chromatographic interaction, as in reversed-phase HPLC. In this study we employed several charged cyclodextrin (CD) derivatives as one of the pseudo-stationary phases for EKC. Because these CD derivatives have both chirality and charge, they can be applied to the separation of enantiomers and/or electrically neutral compounds. For more than 40 enantiomers, phosphated (α, β, γ)-CDs, sulfated β-CD, carboxymethylated (β, γ)-CDs, and carboxyethylated (β, γ)-CDs were tested under both acidic and neutral ~ alkaline conditions in order to investigate the enantioselectivity. Among the tested charged CDs, β-type CDs were effective and about half of the analytes were enantioseparated by EKC with charged CDs, especially with β-CD phosphate or β-CD sulfate. Further, these charged CDs were applied to the separation of some corticosteroids, such as triamsinolone acetonide. These charged CDs were found to be useful as one of the pseudo-stationary phases for EKC.
Keywords: capillary electrophoresis; electrokinetic chromatography; enantiomer separation; charged cyclodextrin; hydrophobic drugs.
Yoshiro Ito
Inorganic Fine Laboratory, Advanced Material Research Center, Kansai Research Institute (KRI), Kyoto Research Park 17, Chudoji Minami-machi, Shimogyo-ku, Kyoto 600-8813
(Awarded by Nagoya University dated March 25, 1997)The characterization of end groups in various practical polymers was carried out by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). In the first basic study, the characterization of end groups in standard monodispersed polystyrenes (PS's) polymerized with n-butyl lithium was achieved. By comparing the intensities of the peaks due to the end groups and the main chain on the pyrogram, the number-average molecular weight of PS up to ca. one million could be directly determined. Through this work, the accuracy and precision of Py-GC/MS for an end group determination were empirically evaluated. In a concerning second study, branched alkyl end groups of poly(methyl methacrylate)s, which were polymerized radically, it became possible to make a determination based on the observed pyrograms. The thus-obtained results demonstrated the practical applicability of Py-GC/MS for the characterization of end groups in industrially synthesized polymers. In third and fourth studies, the end groups in polycarbonates and water-soluble acrylic copolymers were investigated using reactive pyrolysis in the presence of an organic alkali, tetramethylammonium hydroxide. By this method, an accurate and rapid determination of their end groups became possible. Through these studies, Py-GC/MS proved to be applicable for end group determinations in various polymers.
(Received June 29, 1998)Keywords: pyrolysis-gas chromatography/mass spectrometry; polymer; end group; number-average molecular weight; reactive pyrolysis.
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