A new analytical method for determining the diffusion, permeation and solubility coefficients of flavors into food packaging materials has been established. The proposed method for gaseous and aqueous samples is based on the monitoring of the flavors that have passed through a film by a flame ionization detector. One can thus predict the dynamic sorption behavior of flavors in food packaging materials under a low vapor pressure. The factors which affect the sorption behavior were elucidated by using of the present method. In order to improve the sorption property of packaging materials, modifications of the packaging materials by electron-beam irradiation and by hydrolysis for ethylene vinyl acetate copolymer (EVA) and polyethylene films were studied. In both modified films, the sorption depression was observed for volatile compounds with a low solubility parameter (SP) value; this effect resulted from a restriction of the chain mobility by mild crosslinking and a lowering of the affinity by surface polarization for irradiated and hydrolyzed films, respectively. Furthermore, by using the proposed thermodynamic affinity concept, represented as the two- dimensional distance (δ_c) between two SP values of film and flavor, packaging materials with high flavor preservation against sorption can be designed.

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With a low-power radio-frequency generator (1.8kW, 27.12MHz), N₂ and O₂ plasmas were obtained by slightly modifying the load coil and matching circuit. After the Ar plasma was generated, the outer and carrier gases of Ar were gradually replaced by N₂ or O₂. The replacement of the intermediate Ar gas by N₂, however, was impossible. The detection limits of inductively coupled mass spectrometry with the N₂ and O₂ plasmas, in which the outer and carrier gases were 100% N₂ and O₂, respectively, were comparable or lower for the elements with ionization potentials lower than 6.5eV, but generally higher for the other elements, compared to those obtained with the Ar plasma. Polyatomic ions resulting from Ar, such as ArO⁺and Ar₂⁺, were considerably attenuated with the N₂and O₂ plasmas, although the intensities of ArN⁺and analyte oxide ions increased with these plasma, respectively.

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The characteristics of the saccharide mass spectra by the atmospheric pressure spray (APS) method have been investigated. The APS mass spectrum depends on the temperature of the capillary from which fine droplets are produced. Under low-temperature operation, only cationized molecules of saccharides are obtained. Under high- temperature operation, however, fragment ions due to the cleavage of glycosidic bonds appear in the APS mass spectra in addition to cationized molecules. These ions produced by high-temperature operation are very useful for obtaining information concerning the saccharide structure. The APS mass spectra of several saccharides containing cationized molecules and fragment ions are presented.

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Amino acids in natural water have been determined quantitatively in form of L-isomers. At the same time their D/L ratios have been determined by gas chromatography with enantiomer labeling. The water was sampled at Biwako, Kinokawa and Takihata. For an analysis of free amino acids, a batch technique was used to preconcentrate the amino acids by ion- exchange resin of Dowex 50W-X8. For total dissolved amino acids, the water sample was first heated in 6M HCl to hydrolyze the bound amino acids, and then purified by a column packed with Dowex 50W-X8. The major amino acids in natural water samples were found to be Thr, Ser, Asp and Orn in free form, and Gly, Ser, Asp and Glu in total dissolved form. In addition, some amino acids in free form showed high D/L ratio that might be due to the pollution.

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A flow-injection analysis system for the determination of ethanol was developed incorporating an oxygen electrode and an enzyme reactor packed with Sepharose 4B on which alcohol dehydrogenase (ADH) and NADH oxidase (NOD) from Bacillus licheniformiswere co-immobilized. Although the response of the system depended on the concentration of FAD added into a carrier solution, it was linearly related to the ethanol concentration over the range 0.25-1.0mM, even in the absence of FAD, by controlling the immobilized amount of ADH and NOD. The linear relationship between the ethanol concentration and the response in the presence of 60μM FAD was observed over the range 0.1-1.5mM. When the system was applied to the determination of ethanol in various kinds of alcoholic beverages, the results obtained under both conditions were comparable to those obtained by the F-kit method.

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Poly(thionine)-modified electrodes have been prepared using basal-plane pyrolytic graphite, glassy carbon and In-Sn oxide conducting glass as electrode substrates by an electrooxidative polymerization of thionine in both aqueous and acetonitrile media. It was found that the prepared films, the surface concentration of which can be controlled over the range of ca. 10^-10-10^-8mol cm^-2 by appropriately choosing the electropolymerization conditions (e.g., solvent, concentration of thionine and electrolysis time), are electroactive (the formal potential is ca. 0.0V vs. Ag/AgCl at pH 7.0) and chemically stable. The modified electrodes exhibited excellent electrocatalysis for NADH oxidation in neutral aqueous solutions, with an activation overpotential which is ca. 400mV lower than that of a bare electrode. Further, the modified glassy carbon electrode was found to be promising as an amperometric detector for the flow-injection analysis of NADH, typically with a dynamic range of 5μM-1mM.

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A highly sensitive enzyme immunoassay of conjugated 1β-hydroxycholic acid in heterologous combination was developed using horse radish peroxidase labeled antigen. The assay method was optimized for quantitation in double antibody- coated microtiter plates. The assay had a lower limit of sensitivity of 12.5pg/assay. The cross-reactivity for glyco 1β- hydroxycholic acid was 80.13% and those for conjugated 1β-hydroxychenodeoxycholic and 1β-hydroxydeoxycholic acids ranged from 0.13 to 7.58%. The values in dried blood samples obtained by the present method correlated well with those in radioimmunoassay (r=0.964). Concentrations of conjugated 1β-hydroxycholic acid in dried blood spotted onto filter paper in newborns with congenital biliary atresia (737±264ng/ml) were significantly higher than those of normal newborns (261±190ng/ml).

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An enzyme-linked immunoassay (ELISA) for the determination of humic acid in natural-water samples was developed. For antisera production, humic acid was coupled to helix pomatia hemocyanin. A humic acid-horseradish peroxidase conjugate was synthesized as a tracer. The detection limit of this competitive assay was estimated to be 0.5μg/l, which means 100pg absolute. The cross-reactivities at the center point (50%-value) of several commercial humic acids and both aliphatic and aromatic acids were determined. Moreover, the structural aspects of the humic acids could be elucidated.

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Curdlan gel was evaluated as a support for electrophoresis of low molecular weight aromatic compounds in comparison with polyacrylamide gel. This gel was found to have the excellent ability to recognize the positional (o-, m- and p-) isomers of phthalic acid and phenylenediamine, which were not resolved by polyacrylamide gel electro- phoresis. Furthermore, the polysaccharide support gave superior resolution for hydrophilic compounds such as hydroxylated benzoates. Hydrophobic alkylated benzoates were much better resolved in polyacrylamide gel rather than in curdlan gel.

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A liquid-chromatographic (LC) on-column derivatization method coupled with a column-switching technique has been developed for the determination of histamine (Him) and 1-methylhistamine (MH) in biological materials. This method was designed to involve both a sample purification step and a fluorescence derivatization step for the direct application of a deproteinized sample to the LC system. A crude extract of mouse tissue injected onto the LC system was purified on an ion-exchange polymer column, and then Him and MH were derivatized to each fluorophore, followed by chromatography on a reversed-phase C₁₈ polymer column. Optimization of the LC conditions has led to the development of a simple analytical method for the simultaneous determination of Him and MH with good reproducibility and a wide linear range of 0.01-10μg ml^-1. Application of this method to the determination of Him and MH in mouse tissues and fermented soy foods resulted in overall mean recoveries greater than 93% at fortification values of 1-100μg g^-1

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The determination of anions in aqueous solution using an ArF laser is described. Chloride ion can be determined down to a level of 4×10^-7M by measuring the absorption of Cl formed by ArF laser irradiation using a multiple-reflection method with a helium-cadmium laser (λ=325nm) as the monitoring light source. Br^-, I^-, SCN^-and SO₄^2-were determined by measuring the absorption of radicals or hydrated electrons formed upon UV laser irradiation with detection limits of 4×10^-7, 4×10^-7, 1×10^-6-and 1×10^-4M, respectively.

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Surface-enhanced infrared spectroscopy was applied to the trace analysis of secretions on human skin. The secretions were transferred onto silver-coated barium fluoride substrates by pressing the substrates on the skin at several parts of the human body (wrist, palm, cheek, abdomen and sole). The infrared spectra of the substrates were measured by the transmission mode. Small amounts of lactate, triglycerides, fatty acids and fatty acid esters were identified from the secretions. For detecting lactate, the sole is the best sampling point on the human body.

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Color development based on the ion association of molybdophosphate with a cationic dye, a chloro derivative of Malachite Green (Cl-MG), was investigated in an aqueous acidic solution. Cl-MG is very stable as its quinoid form in an acidic medium, and can easily react with molybdophosphate to form a green ion associate, which shows maximum absorption at 685nm. The experimental conditions for optimum color development have been examined. This color development reaction could be applied to the determination of trace amounts of orthophosphate. The molar absorptivity was 1.3×10⁵dm³ mol^-1cm^-1 at 685nm.

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We synthesized a metal chelating sorbent by immobilizing a pyridazine derivative on glass beads and investigated the adsorption and separation behavior of the beads for metal ions. The beads were synthesized by reacting glass beads (amino-aryl-CPG) with 3-chloropyridazine-6-carboxylic acid hydrazide in toluene at 110°C for 12h. The exchange capacity of the beads for copper determined by a batch method was about 0.1mmol g^-1 (glass beads). The beads reacted with various metal ions in several solutions of differing pH, and the degree to which the metal ions coordinated to the pyridazine derivative was indicated by a color change. Using a column method, metal ions were selectively retained, and then quantitatively and separately eluted from the beads by a stepwise elution employing several eluents, including hydrochloric acid. A column packed with the beads was successfully used to determine trace metal ions in both tap-and rain-water samples.

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A sensitive and selective spectrophotometric determination of silver(I) based on an association complex between silveradenine and eosin was established. The apparent molar absorptivity of the complex, without solvent extraction, was 1.1×10⁵dm³ mol^-1 cm^-1 at 560nm. No metal ion interfered in an equimolar ratio of silver(I) among the metal ions examined. The method was applied to assays of silver in silver solder and silver protein: the results were in good agreement with those obtained by ICP-AES. The sensitivity could be further enhanced about 5-10 times over that of spectrophotometry with the third-derivative spectrophotometry and/or the fluorescence quenching method. Thermodynamic parameters (ΔG=-6.34kcal mol^-1, ΔH=-28.17kcal mol^-1 and ΔS=-72.73cal mol^-1 K^-1) and the binding parameters (n=0.98 and K=4.10×10⁴M^-1 at 27°C) suggest that colored complex formed in this reaction system is an association complex between silver-adenine and eosin.

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The extraction of nickel(II) with seven N, N, N-tridentate heterocyclic hydrazones, a neutral form of which is abbreviated as HL, using chloroform or benzene as an extraction solvent has been studied, the extraction equilibria being analyzed on the basis of the data for the proton dissociation of H₃L²⁺, the formation of Ni(HL)²⁺ and Ni(HL)₂²⁺ complexes and the proton dissociation of Ni(HL)₂²⁺ complexes in aqueous solution. Nickel(II) is extracted as NiL₂, although it forms such complexing ions as Ni(HL)²⁺ or Ni(HL)₂²⁺ in the aqueous phase. The distribution constants of HL and NiL₂ (the abbreviations of which are K_d and K_dm, respectively) have been determined under the same condition as in aqueous solution. The logarithmic plots of K_dm vs. K_d displayed two straight lines with slopes of 1.9; one is for hydrazones bearing one pyridyl or one quinolyl ring in the aldehyde moiety and the other for hydrazones bearing another pyridyl ring introduced to the aldehyde moiety. This is attributed to an intramolecular hydrogen bond between the imino hydrogen and the nitrogen of pyridine of the latter hydrazones.

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