BUNSEKI KAGAKU Abstracts

The acid dissociation constants (K_a) of Haloperidol and its degraded product were determined by capillary zone electrophoresis (CZE). Haloperidol is degraded by UV-light irradiation, and 4-(p-chlorophenyl)-4-hydroxypiperidine (CPHP) is generated from Haloperidol. When the irradiated solution was analyzed by CZE, residual Haloperidol and two degraded products were detected. The acid dissociation constant of Haloperidol was determined through the electrophoretic mobility of the residual Haloperidol, and the pK_a value determined was similar to that measured under no degradation conditions, as well as literature values. It was also confirmed that one of the degraded products was assigned to CPHP based on the migration time, the electrophoretic mobility, and its acid dissociation constant analyzed. It was demonstrated in this study that the acid dissociation constants are accurately determined by using CZE, even under degraded conditions of the analyte.

The simultaneous determination of inorganic nitrogen species (nitrite, nitrate, and ammonium ions) in seawater samples was examined by ion chromatography with the addition of EDTAs [ethylenediamine-N,N,N',N'-tetraacetic acid, trisodium salt (EDTA · 3Na) or ethylenediamine-N,N,N',N'-tetraacetic acid, tetrasodium salt (EDTA · 4Na)] to the samples. Nitrite and nitrate ions were separated on a polymer type of anion-exchange column with a high exchange capacity using 1.0 M sodium chloride+5 mM phosphate buffer (pH = 5.0) as an eluent, and were detected by UV at 225 nm. Ammonium ion was detected at 710 nm as an indophenol blue derivative by a post-column reaction in the presence of dichloroisocyanurate and 1-naphthol. The addition of EDTAs (EDTA · 3Na and EDTA · 4Na) to seawater samples was effective to remove the interference by magnesium, calcium, and strontium ions in seawater samples. Also, it did not interfere with the sensitive determination of inorganic nitrogen species. The addition of EDTA · 3Na to real seawater samples was effective for the determination. Calibration curves by the peak-area method for all ions in 35‰ artificial seawater showed good linearity (R²≥0.995) in the range of 0 – 2 mg L⁻¹. The detection limits (S/N = 3) of nitrite, nitrate, and ammonium ions were 0.3 μg L⁻¹, 1.8 μg L⁻¹, and 1.9 μg L⁻¹, respectively. Also, the repeatability (1 mg L⁻¹, n = 5) was below 0.23% (retention time), 1.70% (peak area), and 1.50% (peak height). The present method was applied to the simultaneous determination of inorganic nitrogen species in seawater samples with addition of EDTA · 3Na. The recovery rate by the analysis of spiked samples was in the rage of 98—105%.

The simultaneous determination of nitrite (NO₂⁻), nitrate (NO₃⁻), and phosphate (PO₄³⁻) in seawater samples was examined by ion chromatography. Nitrite and nitrate ions were separated on dilauryldimethylammonium (DDA⁺)-coated monolithic ODS columns using 0.4 M sodium chloride (pH = 5.0) as the eluent, and were detected by UV at 225 nm without any interferences by the major anions in seawater. Phosphate ion was detected at 885 nm by a post-column reaction based on the formation of Molybdenum Blue using sulfuric acid, hexaammonium heptamolybdate tetrahydrate, antimony potassium tartrate, L(+)-ascorbic acid, and sodium dodecyl sulfate. Thus, this method enabled the direct determination of nitrite, nitrate, and phosphate ions in seawater. Calibration curves of all ions in 35‰ artificial seawater by a peak-area method showed good linearity (R²≥0.998) in the range of 0 – 2 mg L⁻¹ for NO₂⁻ and NO₃⁻, and 0 – 2 mg-P L⁻¹ (as phosphorous) for PO₄³⁻. The detection limits (S/N = 3) of nitrite, nitrate, and phosphate were 0.8 μg L⁻¹, 1.6 μg L⁻¹, and 0.09 μg-P L⁻¹, respectively. Also, the repeatability (1 mg L⁻¹ for NO₂⁻ and NO₃⁻, and 1 mg-P L⁻¹ for PO₄³⁻, n = 5) was below 0.05% (retention time), 0.66% (peak area), and 0.69% (peak height). The present method was applied to the simultaneous and selective determination of analytes in seawater samples of Seto Inland Sea. The recovery rate by the analysis of spiked samples was in the rage of 93—105%.

The metal elimination device which used a traditional cation-exchange type suppressor was combined with a suppressed-IC to determine trace anions automatically in metal content samples. First, the removal efficiency of metal ions with the metal elimination device was evaluated, and then a reproduction process of the cation exchanger was established. Next, this inline metal elimination-IC system was evaluated concerning its precision and reproducibility. The system could successfully quantify ppb levels of anions in sample solutions including 400 ppm of copper ion. Finally, the system was applied to the determination of trace chloride in metal salt reagents and a soft etching solution. As a result, a fixed quantity of the chloride ion less than 1 mg kg⁻¹ was possible.

A simple visual method for the determination of arsenic in environmental water after collecting arsenic as arsine in a column packed with silica gel impregnated with potassium permanganate has been developed. The column was prepared as follows: Silica gel (0.4 g) was put into a plastic column (inside diameter 4 mm; column length 110 mm). A potassium permanganate solution and air were passed through the plastic column successively, and then the column was colored red-purple. To 40 mL of the sample solution, potassium iodide, tin(II) chloride, zinc sand and a 6 M hydrochloric acid solution were added to liberate arsine. When the liberated arsine was passed through the column, a colored-band (brown band) appeared in the column (red-purple) because of manganese dioxide (brown) formed by the reduction of potassium permanganate (red-purple) with arsine. There was a good relationship between the length of colored-band and the concentration of arsenic. The concentration of the total inorganic arsenic [As(III)+As(V)] was measured based on the length of the colored band in the column. The established method was applied to hot spring water samples containing high concentrations of iron(II) ion. Significant amounts of arsenic in the hot spring waters were found to be removed from water by the adsorption and/or coprecipitation of arsenic with an iron(III) hydroxide precipitate, which was formed by the oxidation of iron(II) ion.

Due to the aging of Japanese societies, people have become aware of the importance of self-managing of their health, and thus health food has been very popular in recent years. In 2013, the Ministry of Health, Labor and Welfare announced that the elongation of a health of life expectancy is of importance in order to suppress the increment of healthcare spending. Under these circumstances, the market for health foods and supplements is expected to expand. Since there are no strict regulations of the manufacturing and marketing for health foods and supplements, it is said that some products claims positive effects even in the absence of any conclusive evidence. In addition, the amounts of effective components in health foods and supplements are not shown for many products. Under these conditions, determinations of the amounts of the effective components in health foods and supplements is crucial for safety when using these products. In 2013, Consumer Affairs Agency began investigating a new certification mark system concerning the functionality of foods, and has also been going forward in the development of display methods for them. In recent years, vitamin E and polyphenol related products founded in supplements or health foods have been consumed in daily life. Although these products may make consumers think that they are more effective than those foods that contain only one effective component, there is no evidence as to whether several components interact with each other to affect their activity. Therefore, it is of great importance to precisely measure the amounts of the effective components in foods. In this research, we chose multi-component supplements that included vitamin E derivatives and polyphenols, and investigated a rapid analysis method for these active components. Vitamin Es and polyphenols have widely different polarities, and thus rapid measurements of these compounds at the same time is difficult to active by using conventional methods. Thus, we applied an ultra high-speed LC system equipped with a photo-diode array detector to determine the quantities of vitamin E and polyphenols at once, even if they have very different retention times. As a result, eight vitamin E derivatives were found to be able to be analyzed in a short time. In addition, the results of the present work suggested that health foods and supplements are analyzable by our method to provide information about containing effective compounds.

Polyphenols are widely distributed in plant foods, and are responsible for their taste, color, and health benefits. They have been proposed to play a key role in food stability and functions, owing to their ability to self-associate in a nonspecific way and to form colloids-like complexes. Although this behavior was characterized by some molecular analysis, such as NMR spectroscopy and molecular dynamics simulations, the detection of self-associated polyphenols has been difficult due to their instability and complexity. In the present study, we used catechin extract from tea as model polyphenols, and developed a new method for the detection of the self-association of tea polyphenols using native-polyacrylamide gel electrophoresis (native-PAGE). For the detection of the self-association, tea polyphenols were analyzed by native-PAGE/transblotting, followed by redox-cycling staining. The result showed that tea polyphenols were separated into the high-molecular weight region on the gel. In addition, both coomassie brilliant blue and silver staining, the general staining procedures to protein, were applicable to the analysis on the gel without transblotting. Furthermore, the association-dissociation behavior of tea polyphenols was characterized by using both the surfactant and the purified tea catechins. These results indicate that the band detected in the high-molecular weight region involves stable self-associated polyphenols. The detection and characterization of self-associated polyphenols are the important steps to evaluate the quality and functionality of foods including plant polyphenols. In the future, this method must be validated for more general purposes.

Volatile Organic Compounds (VOCs) that are contained in crude oil and natural gas are the leading cause of suspended particulates or photochemical oxidants. Especially, because benzene is a carcinogen, its environmental standards related to air is formulated. We take a variety of VOCs emission reduction measurements in the production and storage processes for oil and gas. In order to monitor those effects, we have been measuring the benzene concentration in air found in oil and gas fields by our own laboratory using a passive sampler method originally used for indoor measurements of VOCs. Since we had planned to outsource these analysis duties to a measurement certification inspection organization, we and that organization had collaborated to carry out comparison experiments between laboratories and between types of passive samplers, for one year. The adsorbent of the passive sampler that we used in the comparison experiment was a carbon molecular sieve and activated carbon. The results indicate a good correlative relationship for both comparison experiments.