Nobuharu Kunita

A New Gas Chromatographic Analysis of Alkyl Benzenesulfonate

For the determination of alkylbenezene sulfonate, Abbotts method has usually been used and its result is always expresed as MBAS. By this method, however, quantitative analysis of ABS itself is not accurate, especially for its small amount.In this paper, we describe a new gas chromatographic analysis of ABS as methylsulfonate by sulfonylation followed by methylation. Flame photometric detector which has a selective sensitivity to sulfur was successfully used for detecting small amount of ABS without any influence of MBAS.Using this method, a linear calibration curve was obtained in the range of 20 to 1000ng and Abbotts method was found to be applied together. At the same time, it was found that ABS and LAS was able to distinguished and that charactaristic patterns of LAS leached from washed container were obtained in this method.

Studies on Analysis of Metal Elements of Foods (II)

Several experimental conditions were examined with regard to the determination of strontium in food by a UHF Plasma Spectra Analyzer. The most suitable experimental conditions were as follows: wavelength Sr II 4077.71A, magnetron anode current 280mA, field current 380mA, plasma gas 3.5L/min, sheath gas 2.5L/min. The intensity of strontium spectrum was influenced with the diverse ions such as iron, calcium, magnesium, potassium and sodium, and the effects of potassium and sodium were remarkable. The calibration curve had preferable linearity and the mean value of the recovery rates in ten experiments for strontium determination was 101.6%.The concentrations of strontium in 6 samples of fruit, tea and 3 samples of unpolished rice were determined by the experimental conditions above mentioned.

Studies on the Analysis of Metal Elements of Food

In order to carry out the simultaneous analysis of metals in foods by UHF Plasma Spectra Analyzer, the optimal conditions were investigated.The most suitable analytical conditions were as followed: magnetron anode current 270mA, field current 360mA, Plasma gas 1.8L/min, sheath gas 3.0L/min. After ashing of the samples, it was found to be suitable for the preparation of solution to use 0.5 N-nitric acid. Measurement of diverse ions was influenced considerably by sodium and potassium, however, the sensitivity was increased by the dilution of solution.The detection limit of each metals in unpolished rice was measured under the conditions above-mentioned, and simultaneous analysis of metals in tangle, coffee bean, spinach, fish (crucian carp) and soybean were examined.

Simultaneous Determination of Manganese, Copper, Lead, Zinc and Cadmium in Unpolished Rice by Atomic Absorption Spectrophotometry

The optimum conditions for the determination of manganese, copper, lead and zinc in unpolished rice by atomic absorption spectrophotometry were investigated, and the satisfactory result was obtained in accuracy and rapidness.The metals in the samples were extracted by nitric acid for the analysis of atomic absorption spectrophotometry, after ashing them by a low temperature asher using the oxygen plasma.The mean values of the recovery rates in ten experiments for manganese, copper, lead and zinc were 99.3%, 100.5%, 98.3%, and 101.6%, respectively, and liner calibration curves were obtained in the range from 0.5ppm to 2.0ppm for manganese and zinc, and from 1.0ppm to 4.0ppm for copper and lead.From these results, it was found that the low temperature ashing-acid extraction method is available for the simultaneous determinations of several metals in the unpolished rice.The concentration of heavy metals in the 60 samples of unpolished rice were determined by the method above mentioned.