The performances of palladium as a matrix modifier for group IIIB-VIB elements in graphite-furnace atomic absorption spectrometry were compared to those of other modifiers hitherto reported. The application of palladium and mixed modifiers containing palladium to biological, mineral sediment or natural water samples is summarized. The addition of palladium generally makes a higher thermal pretreatment temperature possible without any sensitivity loss, thus reducing the interferences of coexisting materials. Mass spectrometry connected to graphite-furnace atomic absorption spectrometry enabled real-time observations of the vaporized species in the furnace and revealed the vaporization and atomization process of arsenic and selenium in the presence of palladium. Both elements form compounds Pd_nM_mO_l (M=As or Se), which are then decomposed to PdM and finally to atomic vapor of M.The performances of palladium as a matrix modifier for group IIIB-VIB elements in graphite-furnace atomic absorption spectrometry were compared to those of other modifiers hitherto reported. The application of palladium and mixed modifiers containing palladium to biological, mineral sediment or natural water samples is summarized. The addition of palladium generally makes a higher thermal pretreatment temperature possible without any sensitivity loss, thus reducing the interferences of coexisting materials. Mass spectrometry connected to graphite-furnace atomic absorption spectrometry enabled real-time observations of the vaporized species in the furnace and revealed the vaporization and atomization process of arsenic and selenium in the presence of palladium. Both elements form compounds Pd_nM_mO_l (M=As or Se), which are then decomposed to PdM and finally to atomic vapor of M.

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Lead(II) was generated from an amalgamated lead anode in solutions containing 0.2-1M potassium nitrate and 30% ethanol with a 100% current efficiency over a wide range of current densities. Sodium oxalate reference materials, dried at 200°C for 1h, were titrated coulometrically with electrogenerated Lead(II), with a relative standard deviation of 0.012%. A sharp end point of the precipitation reaction was detected amperometrically with a dropping mercury electrode in the presence of ethanol in the electrolyte. The results were in good agreement with the certified values based on a comparison with primary standards for oxidation-reduction titrations.

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An assay method for determining organic hydroperoxides based on indamine dye formation using a water-soluble iron-(III) porphyrin as catalyst was developed. The assay was performed at pH 4.4 under anaerobic conditions and was applicable to flow-injection analysis. t-Butyl hydroperoxide was determined over the range of 1 to 40 nmol with r=0.999 and SD(%)=2.4 (n=5 at 4.8nmol). The mechanism of the catalytic reaction is discussed based on kinetic measurements, suggesting a general acid-base catalyzed reaction involving a heterolytic cleavage of the O-O bond.

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Kinetics and thermodynamics of the inclusion reaction of flavonols with β-cyclodextrin have been studied fluorometrically in 30%v/v methanolic aqueous solution. The equilibrium constants of this reaction were determined for flavonol and its 12 different hydroxy and methoxy derivatives in acidic and alkaline media where each flavonol is present quantitatively as fully protonated or deprotonated species. A thermodynamic consideration on the substituent effects reflected in these constants leads to a model for the present inclusion complex. With the inclusion constants for a monoprotic flavonol and its conjugate base, the effect of β-cyclodextrin on the acid dissociation equilibrium of the flavonol is quantitatively described. Kinetic aspects of this inclusion reaction are also discussed.

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The rate of back-extraction of tris(acetylacetonato)cobalt(III), Co(acac)₃, in carbon tetrachloride containing acetylacetone, Hacac, by washing with aqueous 4mol dm^-3 perchloric acid-sodium perchlorate solutions is studied. In the early stage, a rapid back-extraction which is due to the two-phase distribution of the complex is observed; the transient distribution equilibrium established is dependent on the acid concentration. This is explained in terms of the formation of protonated species, Co(acac)₃H⁺ and Co(acac)₃(H⁺)₂. When the two phase agitation is continued, the back-extraction proceeds gradually. The rate is dependent on the acid concentration but it is not dependent on the Hacac concentration. Most cobalt back-extracted in this stage is found to be in the bivalent state. The rate-determining step is concluded to be the dissociation of the first acetylacetonate ion from the complex in the aqueous phase, which is followed by the reduction of cobalt(III) to cobalt(II). The rate constants of the dissociation of acetylacetonate ion from the Co(acac)₃H⁺ and from the Co(acac)₃(H⁺)₂ are one and two orders higher than that from the Co(acac)₃.

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A dextrane-polyacrylic acid mixture was found to be a good phase-separating agent for aqueous solutions and to be applicable to the solvent extraction of tris(1, 10-phenanthroline)iron(II) ([Fe(phen)₃]²⁺). Iron(II) was extracted as an ion-pair with polyacrylic acid. Such extraction conditions as the mixing ratio of two polymers, the pH, and the temperature during centrifuging were examined.

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Bis(O, O′-dipropyl dithiophosphato)nickel(II) is soluble in ethanol and absorbs light at 524nm (molar absorptivity, ε, is 91mol^-1 dm³ cm^-1) and 688nm (ε is 74mol^-1 dm³ cm^-1). In water-ethanol mixed solvents, however, part of the complex dissociates into nickel(II) and O, O′-dipropyl dithiophosphate ions, and the absorbances at 524 and 688nm depend on the water content. This property of the complex can be utilized for the spectrophotometric determination of the alcohol content of alcoholic drinks. The method proposed is as follows: 6cm³ of sample drink cooled to 15°C and 14cm³ of a 14.3mmol/dm³ ethanolic solution (its temperature being adjusted to 25°C) of a nickel(II) complex are mixed. After the mixture is warmed to 25°C, the absorbance is measured at 524 or 688nm. The alcohol content is calculated by using calibration graphs. This method is simple, rapid, accurate and suitable for the analysis of shochu, whisky, brandy and vodka. This method is also applicable to the analysis of sake, wine and beer, provided that a distillation step as a pretreatment is introduced into its procedure.

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The formation of thiocyanate was achieved by the oxidation of sulfide with hydrogen peroxide in the presence of cyanide. The thiocyanate formed from the sulfide was extracted into 1, 2-dichloroethane using Methylene Blue and the extract was measured spectrophotometrically at 657nm for the determination of sulfide. Hydrogen sulfide, separated from sample matrix, was introduced into a solution containing cyanide and hydrogen peroxide, in which the hydrogen sulfide was completely converted into thiocyanate. A linear calibration graph was obtained over the range 5×10^-7-1× 10^-5M (M=mol dm^-3) sulfide (0.16-3.2μg of S^2- in 10ml (ml=cm³)) and the apparent molar absorptivity for sulfide at 657nm is 8.28×10⁴l mol^-1 cm^-1. The proposed method gave a relative standard deviation of 1.22%at the 5×10^-6M sulfide level when applied to hot-spring water samples.

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Effects of digital image processing on improvement of images acquired with a fiber-optic microscope system were estimated. A raw image of cultured cells stained with a fluorescent dye was noisy and had insufficient contrast for observation of a detailed image. To improve the image quality, two series of techniques were performed. For observations of static specimens, integration of consecutive frames was effective in reducing the random noise. Histogram transformation operations improved the contrast of the integrated images, providing a clearer detailed image. For observations of moving specimens, spatial filtering for smoothing the image acquired by freezing one frame was effective in reducing random noise. The contrast of the image was also enhanced with the same histogram transformation operations. Spatial filtering for the purpose of sharpening images enhanced the partition patterns of optical fibers constituting the fiber-optic plate. They were successfully removed by two-dimensional fast Fourier transform.

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Although the bulbed capillary chemical shifts of benzene, Bromoform and chloroform are considerably varied in pure liquids and some binary systems, these shifts can be systematically explained as decided primarily by their "intrinsic" intramolecular effects and secondarily by their intermolecular effects. The intermolecular and intramolecular effects associated with the anisotropy effects of benzene and the electronegativity effects of bromoform or chloroform can be systematically understood from their crystal structure models. The Intramolecular and intermolecular effects of the three species are evaluated numerically by systematically comparing their shift data with each other. More benzene than 1:1 to be probable in a benzene-chloroform or benzene-bromoform system is discussed in some detail based on the evaluated numerical values of the intermolecular effects and measured shift displacement data in these systems.

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The characteristics of an argon-matrix inductively coupled plasma (ICP) containing small amounts of nitrogen gas are considerably different from those of a pure argon ICP. The role of nitrogen in the mixed gas ICP is investigated from spectroscopic analyses of argon emission lines. The spectral widths of the argon and hydrogen lines increase with the amount of nitrogen gas added, which means that the electron number density of the plasma is raised. The emission intensities of the argon and zinc lines also increase, and the variation in these intensities corresponds to that in the spectral width of the argon and hydrogen lines when nitrogen is added in the plasma. These observations suggest that the nitrogen addition causes a great change in the region of the ICP from which the argon lines are dominantly emitted. Furthermore, the intensity of the NO band heads decreases in the argon-nitrogen mixed gas ICPs, implying that the increment in the plasma temperature contributes to the decomposition of NO radicals.

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A gas-chromatographic method is described for the determination of tributyltin and triphenyltin compounds in fish. Fish tissue was hydrolyzed with a potassium hydroxide/ethanol solution. Organotin compounds were extracted with toluene. The extract was purified with a series of cation- and anion-exchange resin cartridges. Organotin compounds were propylated and then determined by gas chromatography with flame photometric detection. Separation of the organotin compounds was carried out using a Silicone OV-1 packed column and an Ultra-1 capillary column. Organotin compounds were stable during hydrolysis for 90min at 60°C. The detection limits of the two organotin compounds in their chloride forms were 0.06ng (6ng/g for 5g of the sample) for tributyltin compounds and 0.1ng (10ng/g for 5g of sample) for triphenyltin compounds. Compounds yielding propyltributyltin and propyltriphenyltin were found in fish at levels ranging from none detected to 120ng/g, and 10 to 520ng/g in their chloride forms.

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A new reagent, 2-(6-methyl-2-benzothiazolylazo)-5-diethylaminophenol (MBTAE), which was synthesized for the first time by us, was used as a precolumn derivatizing reagent in the determination of platinum metals and some transition metals by reversed-phase HPLC. The effects of the composition and general properties of the mobile phase, column temperature and foreign ions on the retention behavior of the metal-MBTAE complexes are discussed in detail. The platinum metals and some transition metals can be separated on a Spherisorb C₈ column at a detection wavelength of 575nm using a 73/27(v/v) methanol/water containing 20mmol/l pH 6.0 acetate buffer and 12mmol/l malic acid as the mobile phase. The detection limit of each metal ion is as follows (ng); Ru 1.77, Rh 0.057, Pd 0.17, Os 0.89, Ir 0.47, Pt 0.55, Co 0.18 and Ni 0.06, respectively, when the signal-to-noise ratio is 2. This method has been used to analyze mineral and anode slime samples. The results correspond to the certified values, and quantitative metal recoveries were obtained

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