水蒸気蒸留法による魚介類中のアルキル水銀定量

Abstract

The steam distillation method for the determination of alkyl mercury in fish and shells is described: The wet samples (5-50g) are put into 500ml distilling flasks and are steam distilled after adding 40ml of 6N hydrochloric acid and 40g of sodium chloride. The aqueous distillate is put into 10ml of 3N hydrochloric acid, final volume being about 180ml. The aqueous distillate is transferred into a 200ml volumetric flask and diluted with distilled water. A 50ml portion of aqueous distillate is transferred into a separating funnel and the alkyl mercury in the aqueous distillate is extracted with a 30ml, then a 20ml portion of benzene, after which it is reextracted with 10ml of 1% cysteine acetate solution. A 5ml portion of the cysteine acetate layer is removed into a digestion flask. Alkyl mercury in cysteine acetate solution is wet-digested by the method previously reported, and is determined by flameless atomic absorption The study has shown that the alkyl mercury, that is, the methyl, ethyl or butyl compound, is entirely distilled by steam distillation, but phenyl of inorganic mercury is not. By the steam distillation method herein described, alkyl mercury in fish and shells can be completely extracted without emulsification. The data have shown quantitative recovery of methyl mercury added to a variety of samples. The coefficient of variation for repeated determinations on a tuna meat sample has been 2.0%.