DETERMINATION OF MERCURY SPECIES IN FISH REFERENCE MATERIALS BY ISOTHERMAL MULTICAPILLARY GAS-CHROMATOGRAPHY WITH ATOMIC-EMISSION DETECTIONAFTER MICROWAVE-ASSISTED SOLUBILIZATION AND SOLVENT-EXTRACTION

A simple and rapid procedure for the simultaneous determination of met hylmercury and Hg2+ in fish reference materials was developed. The pro cedure was based on a rapid (2.5 min) microwave-assisted solubilizatio n of biomaterial with tetramethylammonium hydroxide, simultaneous quan titative ethylation-extraction of the mercury species into hexane (15 min) and flash isothermal separation (15-30 s) using a multicapillary regular column (100 cm) or a minicolumn (22 cm). The chromatographic h ardware necessary for sample introduction into a microwave induced pla sma was downscaled to a split injection port and a 20 x 20 x 10 cm com partment (housing the 1 m column) or a 22 cm x 1 cm od thermally insul ated tube (housing the minicolumn) maintained at a constant temperatur e and connected directly to the detector. No dilution of the GC eluent (60-120 ml min(-1)) with make-up gas was necessary to achieve optimum sensitivity, Detection limits (as Hg) were 0.5 pg mu l(-1) (20 ng g(- 1) dry mass) and 2 pg mu l(-1) (80 ng g-l dry mass)for MeHg+ and Hg2+, respectively. The method was validated for speciation analysis for me rcury in BCR 463, BCR 464 (Tuna Fish) and NRCC DORM-1 (Dogfish Mussel) certified reference materials.