DIRECT GC DETERMINATION OF METHYLMERCURY CHLORIDE ON HBR-METHANOL-TREATED CAPILLARY COLUMNS

Gas chromatography with electron capture detection (GC-ECD) for the an alysis of methylmercury chloride (MMC) using a packed column and a cap illary column has been investigated. The columns were 2 % silicone OV- 227 Uniport HP glass column and a DB-17 capillary column, each pretrea ted by about ten injections of HBr-methanol solution. MMC was separate d as a sharp peak by the HBr-teated column and determined directly by ECD without derivatisation. The mass spectrum of MMC indicated that ha lide exchange from chloride to bromide proceeded during separation. Th e minimum detectable concentrations were approximately 5 ng mL(-1) on the packed column, and 2 ng mL(-1) on the capillary. Calibration curve s showed good linearity between 5-200 ng mL(-1) for the packed column, and between 2-200 ng mL(-1) for the capillary. Relative standard devi ations of peak areas were 0.95 % for the packed column and 0.43 % for the capillary at the level of 100 ng mL(-1) in both cases. The column treatment technique was applicable to determination of methylmercury i n fish samples.