Determination of methyl mercury in water samples with electromagnetic induction thermal desorption/pyrolysis coupled to atomic fluorescence spectrometry

A novel non-chromatographic method for the pre-concentration and determination of trace methyl mercury in water samples has been proposed. This method included two main steps: (1) The methyl mercury in sample solution was adsorbed on PDMS of the Fe/SiO₂/PDMS bed enrichment column; (2) the analyte was thermally desorbed from the enrichment column and pyrolysed to Hg⁰ in an iron particle bed pyrolysis column by using electromagnetic induction heating technique, and then detected by an on-line coupled atomic fluorescence detector. Several factors affecting the enrichment column preparation and concentration procedure have been investigated and optimised. Under optimal condition, the detection limit (3σ) was 0.2 ng L^–1, along with relative standard deviations of 2.4% (10 ng L^–1, N = 11) for the repeatability study. The enrichment factor obtained was 108. The two standard reference materials (GBW08675, GBW10029) were analysed to validate the present method. This method was successfully applied to the determination of ng L^–1 methyl mercury in water samples.