Vol. 50 No. 10
October, 2001
Morihide Higo*
* Department of Applied Chemistry and Chemical Engineering, Faculty of Engineering, Kagoshima University, 1-21-40, Korimoto, Kagoshima 890-0065
(Received 6 March 2001)Inelastic electron tunneling spectroscopy (IETS) is an alternative molecular spectroscopy with high sensitivity and good resolution using electron tunneling through a metal/insulator/metal (MIM) junction at cryogenic temperatures. IETS is a unique surface and interface analytical technique of very thin (nm) insulator films and adsorbed species on them. The tunneling junction is a good model system for oxide catalysts, electronic devises, and solid state sensors. Information about the surface states of alumina and magnesia, adsorption states and chemical reactions of adsorbed species occurring on these oxides, and structures of evaporated thin films is obtained through an analysis of the tunneling spectra. The principles (§2) and theories (§4), advantages and disadvantages (§4), experimental techniques and measuring circuits (§3), and applications in various fields are reviewed comprehensively. The surface characterization of alumina and magnesia (§5), adsorption and surface reactions of organic acids, alcohols, phenols, esters, amines, amides, and nitryls, etc. on these oxides (§6) are reviewed. The applications of IETS to infusion doping through the top metal electrode on the oxide (§7), supported transition metal particle catalysts (§8), evaporated films of Si, Ge, and their oxides (§9), electronic transition and electron resonance of metal complexes and polycyclic compounds (§10), and combination of scanning tunneling microscope (STM) (§11) are also introduced.
Keywords : inelastic electron tunneling spectroscopy (IETS); metal/insulator/metal (MIM) junction; vibrational and electronic spectrum; surface and interface analysis; model systems of catalysts, electronic devices, and sensors.
Toshiaki Hattori, Hagane Irikura and Masanao Kato*
*Research Center for Chemometrics, Toyohashi University of Technology, 1-1, Hibarigaoka, Tempaku-tyo, Toyoha-shi, Aichi 441-8580
(Received 11 July 2001, Accepted 24 August 2001)An ion sensor with plasticized poly (vinyl chloride) membrane containing potassium tetrakis (4-chlorophenyl) borate was developed for measuring of concentration of ethanol in sake as a non-distilled liquor including high concentration of ion matrixes. The effect of ions that were included in the sake on the potential response was investigated. The co-existence of cations, such as organic amines, strongly interfered with the potential response, though anions didnot. The addition of KCl was effective in reducing the interference of cations. However, the reductive effect was insufficient for measuring of ethanol concentration in sake. Therefore sake was treated with a mixed cation and anion exchange resin before the measurement. The ion sensor measurement established with the ion-exchange pretreatment provided a quantitative result, such that the measured concentration agrees with the concentration obtained by gas chromatography within 1%.
Keywords : flow-through ion sensor; ethanol; amphiphilic ion; sake; ion-exchange.
Terumi Miyazaki*, Kiwao Kadokami**, and Hideyuki Tukamoto*
*Sinnikka Environmental Engineering Co., Ltd., 46-80 Nakabaru, Sakinohama, Tobata, Kitakyushu-shi, Fukuoka 804-0002
**Kitakyushu City Institute of Environmental Sciences, 1-2-1 Shin-ike, Tobata, Kitakyushu-shi, Fukuoka 804-0082
A method for the simultaneous determination of 26 hydrophilic and volatile compounds (alcohols, nitriles, esters, ethers and pyridines) in water samples has been developed using solid-phase microextraction (SPME) and GC/MS. The GC conditions were first investigated to obtain sharp peaks. After that, the types of SPME fiber and salting-out reagents as well as the extraction time and sample volume were studied to increase the extraction efficiencies of the target compounds. After internal standards and sodium chloride were added to a water sample, the target compounds were extracted with a SPME fiber for 1 hour. The target compounds were then desorbed by heating the fiber in a GC insert. The determination was carried out by GC/MS-SIM. The results of the overall recovery tests of 26 compounds spiked into bottled water at concentrations 0.01 to 5 µg/l showed that the mean recovery was 99.9% and the mean relative standard deviation was 11.7%. The detection limits ranged from 0.005 to 3.9 µg/l. The method was applied to analyses of river water, seawater and an effluent. Several compounds were detected from ng/l to µg/l level. From these results, it was confirmed that the method can be applied to not only environmental waters, but also effluents containing many matrix.
Keywords : solid-phase microextraction; SPME; hydrophilic compound; volatile compound; water sample.
Yuji Suzuki*
*Saitama Prefectural University Junior College, 820, Sannomiya, Koshigaya-shi, Saitama 343-8540
(Received 5 June 2001, Accepted 13 September 2001)Aromatic aldehyde has been known to react with serum globulin, and p-dimethylaminbenzaldehyde was applied to the determination of the serum globulin concentration. However, the color reaction of this aldehyde with serum globulin was slow. Thus, the author examined the color reaction of eight aromatic aldehydes with serum globulin in order to select an aromatic aldehyde suitable for application to a laboratory examination which requires rapidity. Of the eight aromatic aldehydes, p-nitrobenzaldehyde (p-NITBA) exhibited an excellent property, and in the presence of light gave a colored product with an absorption maximum at about 600 nm in its reaction with serum protein other than serum albumin. The reaction rate increased with increases in the intensity of light and in the concentration of hydrochloric acid; the color reaction was almost completed within 20 min in the presence of light of 3000 luxes when a color reagent containing 2 g of p-NITBA in 1000 ml of a 8.4 mol/l of hydrochloric acid solution was used. The apparent molar absorptivity of serum γ-globulin was 2.15×108 mol-1cm2, and the rate constant at 37°C was 0.202 min-1 for γ-globulin and 0.201 min-1 for serum, which was two-times as large as that of p-dimethylaminbenzaldehyde. The measured values obtained by the proposed method correlated well with those by a method of Goldenberg et al (r=0.990) and by a method that combines the biuret method and the dye-binding method (r=0.967).
Keywords : serum total globulin assay; spectrophotometry; p-nitrobenzaldehyde; light-dependent color reaction.
Eiichi Sudo, Yasuo Esaki and Motoyasu Sugiura*
*Toyota Central R&D Labs. Inc., 41-1, Nagakute, Nagakute-cho, Aichi, 480-1192
(Received 26 July 2001, Accepted 10 September 2001)Liquid chromatography/infrared spectroscopy (LC/IR) using surface-enhanced infrared absorption spectroscopy (SEIRAS) was designed in order to develop a highly sensitive and speedy analysis method of polymer additives. A metal film on the substrate for LC/IR was prepared using the diode sputtering method. The conditions for the preparation of the metal film and the LC/IR measurement were optimized. It was found that the highest sensitivity was obtained by using the following conditions: a metal film of Ag, a substrate of BaF2, and a flow rate of N2 gas for spraying the LC eluent of 3.0 l/min. By LC/IR under these conditions, the determination of triphenylphosphate became possible at a 10 ng detection limit. An enhancement factor of about 90 was obtained. The actual applications to the analysis of additives in commercial polypropylene proved that this method is useful for a highly sensitive analysis of polymer additives.
Keywords : LC/IR; surface enhanced infrared absorption spectroscopy (SEIRAS); additives in polymer; polypropylene.
Shigenori Mukai and Eiko Nakamura*
*Department of Environmental Sciences, Faculty of Education and Human Sciences, Yokohama National University, 79-2, Tokiwadai, Hodogaya, Yokohama 240-8501
(Received 3 July 2001, Accepted 20 August 2001)Filtration with a membrane filter was studied to remove cationic surfactants (CS) which interfered with the spectrophotometric determination of nonionic surfactants (NS) with thiocyanate-iron(III) or thiocyanate-cobalt(II). Materials of the filter, filter pore size and suction rate were studied to separate NS from CS. After the addition of anionic surfactants (AS) to a sample solution, the sample solution was filtered with a polyvinylidenedifluoride membrane filter (pore size 0.1 µm). NS in the sample solution was filtered through the filter, while CS associated with AS remained on the filter. The NS in the filtrate was extracted into toluene with thiocyanate-iron(III), and was measured spectrophotometrically. The procedure was as follows: one milliliter of LAS solution (0.5 mg/ml) was added to a 50 ml sample, which was filtered at a suction rate 3-6 ml/min. After washing the filter with water, 5 ml of a sodium chloride solution (2 M) and 10 ml of toluene were added to the filtrate and NS in the filtrate was extracted into toluene by shaking for 2 min. After standing for 30 min, 5 ml of a potassium thiocyanate solution (10 M), 5 ml of an iron(III) chloride solution (1 M) and 1 ml of a sodium chloride solution (2 M) were added to the toluene solution and the mixture was shaken for 2 min. NS associated with thiocyanate-iron(III) was formed in the toluene layer, and its absorbance was measured at 510 nm. Good results were obtained in recovery tests using sample solutions containing NS in the range of 0~0.1 mg/50 ml as heptaoxyethylenedodecylether. This filtration method is easier than the usual ion exchange method.
Keywords : determination of nonionic surfactants; separation of nonionic surfactants from cationic surfactants; membrane filter.
Yuzo Tamari*
*Faculty of Science and Engineering, Konan University, 8-9-1, Okamoto, Higashinada-ku, Kobe 658-0072
(Received 21 May 2001, Accepted 14 September 2001)Trace phosphate ion was determined by a specrofluorometric method using Rodamine B (RB+) as an ion-pair reagent. Under a sulfuric acid solution, RB+ formed an ion-pair with molybdophosphate ion produced by the reaction of the phosphate with molybdate. A RB+-molybdophosphate as an ion-pair was collected on a membrane filter, washed, dissolved with methylcellosolve, and then measured. The analytical procedure was as follows. Into a centrifugal tube (50-ml volume) 20 ml of a water sample was taken and 1.5 ml of 10 mol/l sulfuric acid was added; the mixture was made homogeneous by shaking for 3 min at 300 rpm. Then, 3 ml of a 5×10-2 mol/l ammonium molybdate solution was added, and the mixture was shaken for 3 min at 300 rpm. After two ml of a 5×10-4 mol/l RB+ solution was added, the mixture was also shaken in the same manner dilution to 30 ml with water. The generated ion-pair precipitation was collected on a membrane filter (pore size, 3 µm) by filtering, washed with 1.5 ml of 0.5 mol/l sulfuric acid 20 times, and dissolved with methlcellosolve including the filter. After dilution to 1/50 with methlcellosolve, the ion-pair solution was measured (Ex 558 nm; Em 577 nm). The detection limit for the determination and precision of this method was 0.1 ppb phosphorus(V), and 1.9% as RSD obtained for 7 determinations of a standard 10 ppb solution, respectively. The present method was applied to commercially available samples of groundwater and mineral water. The analytical values of phosphorus(V) obtained by this method almost agree with those of a spectrophotometric Molybdenum Blue method.
Keywords : phosphate; land water; fluorometry; Rodamine B; ion pair; filter collection.
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