Determination of total mercury in human whole blood by electrothermal atomic absorption spectrometry following extraction

Abstract

An electrothermal atomic absorption spectrometric based method is described for the determination of total mercury in human whole blood. The blood is first treated with dilute hydrochloric acid to free the mercury species bound to protein thiol groups, then a pH buffer and a complexing agent (diethyldithiocarbamate) are added and the mercury species are extracted into toluene. In initial experiments, total mercury was determined in the toluene extract by electrothermal atomic absorption spectrometry. Recoveries of methyl-, ethyl- and phenylmercury chloride and mercury(II) chloride added to blood were better than 95% at concentrations up to about 30 µg dm^–3. However, problems with excessive background absorbance were frequently observed, which could be overcome by back-extraction into dilute hydrochloric acid; this modification being adopted in the proposed method. The accuracy of the method was confirmed by the determination of total mercury in three lyophilized, human whole blood samples (Seronorm), the results demonstrating good agreement with the reference values.