Determination of mercury species in sea-water by liquid chromatography with inductively coupled plasma mass spectrometric detection

A liquid chromatographic method coupled with inductively coupled plasma mass spectrometry for the speciation of methylmercury chloride, mercury(II) chloride and ethylmercury chloride in sea-water is described. The three species were eluted from a C-18 column (150x3.2 mm id) at 260, 340 and 750 s, respectively, with a mobile phase of 1% v/v acetonitrile and 0.005% 2-mercaptoethanol in 0.06 mol l(-1) ammonium acetate pumped at 1.0 ml min(-1). The total mercury determined in TORT-1 Lobster Hepatopancreas (350+/-62 mu g l(-1)) was in good agreement with the certified value (330+/-60 mu g l(-1)). The detection limits (3s) in artificial sea-water were 0.25 mu g l(-1) for methylmercury chloride and mercury(II) chloride and 0.75 mu g l(-1) for ethylmercury chloride. Off-line preconcentration using a dithiocarbamate (Dithiochel) resin gave detection limits (signal-to-noise ratio=2) of 16 ng l(-1) for methylmercury chloride and 17 ng l(-1) for mercury(II) chloride using a 50-fold preconcentration factor for a 1 l sample of synthetic sea-water.