Determination of Mercury in Biological and Environmental Samples by Inductively Coupled Plasma Mass Spectrometry With the Isotope Dilution Technique

Abstract

The accurate and precise determination of total mercury (Hg) in biological and environmental samples by isotope dilution-inductively coupled plasma mass spectrometry (ID-ICP-MS) is described. The precision of Hg isotope ratio ( e.g. , ²⁰⁰ Hg/ ²⁰² Hg) measurements at the 20 ppb level was <0.5%. The deviation of the measured isotope ratios in a standard Hg solution was <0.5% from the natural ratios. Neither spectral interferences nor matrix effects were found to affect the accuracy and precision of the proposed Hg isotope ratio analysis. Total Hg concentrations in human hair and sediment CRMs were determined by ID-ICP-MS after ²⁰² Hg addition and acid decomposition of the samples. Solvent extraction and back-extraction was used for sediment analysis. The various decomposition methods used for hair samples, i.e. , microwave digestion and the Teflon vessel double digestion method, did not give any difference in the analytical value. The ID-ICP-MS results were better than those obtained with standard additions or internal standardization in terms of accuracy and precision. Analytical results for human hair and sediment CRMs were in good agreement with the certified/reference values.