METHYLMERCURY DETERMINATION BY PURGE AND TRAP-GC-FTIR-AAS AFTER NABH4DERIVATIZATION OF AN ENVIRONMENTAL THIOSULFATE EXTRACT

A method of detecting methylmercury species (MeHg) and dimethylmercury (DMM) has been studied. MeHg was transformed prior to its determinati on as methylmercury hydride (MMH) by use of NaBH4. The two volatile fo rms of organic mercury were detected by a purge and trap (PT) unit in- line with a gas chromatograph (GC) connected with a Fourier transform infrared spectrometer (FTIR) which was also in-line with an atomic abs orption spectrometer (AAS). Environmental samples were analyzed by thi s technique. MeHg was detected in thiosulfate extracts of fish and sed iment, and MeHg and DMM directly in water samples. Picogram levels of sensitivity were obtained, the limit of detection being 100 pg for MeH g and 50 pg for DMM. The calibration graph was linear for both compoun ds up to 10 ng as Hg.