Sensitive Method for the Determination of Alkyl Mercury in Fish and Shellfish by the Flameless Atomic Absorption Spectrophotometry

Abstract

A sensitive method for the determination of alkyl mercury in distillate gained by steam distillation was described.
The wet samples (5-50g) were put into a 500ml distilling flasks and steam distilled after adding 40ml of 6N hydrochloric acid and 40g of sodium chloride. The distillate was put into 10ml of 3N hydrochloric acid, being about 180ml of final volume. The distillate was transferred into a 200ml volumetric flask and dilute with distilled water. A 50ml portion of distillate, 20ml of distillated water, 2ml of 0.4% cupric sulfate solution and 20ml of 40% sodium hydroxide solution were transferred into a reaction vessel and mixed togather by slightly shaking, then mercury vapor generated by addition of 10ml 5-% stannous chloride solution determined by flameless atomic absorption spectrophotometer equipped with integration apparatus.
By this procedure herein described, alkyl mercury in a wide variety of fish and shellfish could be sensitively determined. The data have shown quantitative recovery of alkyl mercury added to a variety of samples. The coefficient of variation for repeated determinations on a black bream meat sample was 1.9%.
If the flameless atomic absorption spectrophotometer was not equipped with integration apparatus, alkyl mercury in distillate could be determined from peak height (conc. method) as sensitive as the integration method mentioned above, by raising reaction temperature of reduction to about 40°C.