Spectrophotometric determination of methylmercury in fish tissue with dithizone using a dual-wavelength procedure

Abstract

A dithizone spectrophotometric procedure is described for the measurement of trace concentrations of methylmercury salts. The application of a simple equation using absorbance measurements taken at two wavelengths cancels out small differences in excess of dithizone arising between blank and sample, thus ensuring good precision in the range 0.1–4.0 µg ml^–1.

The developed method is used in combination with the Westöö extraction procedure to determine methylmercury concentrations in fish tissue. A crab meat sample contained less than 0.04 µg g^–1, and values for eight tuna fish ranged from 0.08 to 0.41 µg g^–1.