The aim of this project was to develop a routine analysis method for determining mercury species in whole blood samples using liquid chromatography coupled to inductively coupled plasma mass spectrometry (LC-ICPMS). The developed method separated inorganic mercury and methyl mercury species and was used to analyse low level blood samples from an unexposed UK cohort (n=262). The sum of the species detected were compared with total mercury in blood results analysed by ICPMS following sample dilution in an alkaline diluent.

The optimised method extracted the mercury species from 50 µL of blood sample in a HCl/methanol/L-cysteine solution1. The samples were diluted finally 1 in 25 and the extract was injected on a C18 HPLC column.

Matrix matched standards were necessary, as was the addition of rhodium as an internal standard. The limit of quantification in undiluted blood samples for each species was 0.2 µg/L. Using a spiked blood material at 1 µg/L for each species, which was then diluted and extracted, the between day variation for the method was 8.9% for inorganic mercury and 7.9% for methyl mercury. Interestingly, commercially bought blood quality control samples (Clinchek, Recipe, Germany and Bio-Rad, UK) were seen to contain both methyl and inorganic mercury (although not certified as separate species) and these were used as QC materials throughout the analysis.

The method developed was suitable for detecting low concentrations of mercury species in blood samples and the correlation between the sum of the species and the total mercury results was very good at r=0.94