Comparison of different derivatization approaches for mercury speciation in biological tissues by gas chromatography/inductively coupled plasma mass spectrometry

A novel interface design for coupling gas chromatography and inductively co upled plasma mass spectrometry (GC/ICP-MS) was used to perform mercury spec iation in biological tissues. Three derivatization approaches were optimize d and compared for this purpose: anhydrous butylation using a Grignard reag ent, aqueous ethylation by means of NaEt4B and aqueous propylation with NaP r4B. The last reagent was synthesized in the laboratory as it is not commer cially available. Detection limits obtained by GC/ICP-MS ranged between 100 and 200 fg (as absolute mass) for methylmercury and between 500 and 600 fg for inorganic mercury using a 1 mu l injection, Quantification of methyl- and inorganic mercury was carried out by resorting to aqueous calibration, using ethylmercury as internal standard for both propylation and butylation derivatization techniques. For ethylation procedures, a methylpropylmercur y solution was used as internal standard. The absence of transmethylation d uring sample preparation was checked using a 97% enriched Hg-202 inorganic standard. The accuracy of the three derivatization approaches was evaluated by the analysis of the certified reference material DOLT-2 (dogfish liver) from the National Research Council of Canada and certified for methylmercu ry, with satisfactory results. Copyright (C) 2000 John Wiley & Sons, Ltd.