DETERMINATION OF METHYLMERCURY IN FOOD COMMODITIES BY GAS-LIQUID-CHROMATOGRAPHY WITH ATOMIC-EMISSION DETECTION

A method was developed for determining methylmercury in various food c ommodities. The organomercurial species was converted to methyl-mercur ic chloride by treatment of a sample homogenized with 1.8M HCl. The re sulting chlorinated species was eluted from a Celite 545-sample homoge nate column with methylene chloride. The eluate was treated with stann ic chloride, and the analyte was isolated from coextractives by using a wide-bore capillary column with microwave-induced plasma atomic emis sion detection. The method was applied to both high- and low-moisture commodities during analysis of 32 samples of grains, cereal products, fruits, and vegetables. Methylmercury was found at trace levels (i.e., between a signal-to-noise ratio of 3:1 and 10:1) and up to 0.85 ppb. Recoveries of added methylmercury ranged from 70.0 to 114.0%. Limits o f quantitation and detection were 0.63 and 0.24 pg an column, respecti vely, corresponding to 0.30 and 0.11 ng Hg/g sample for a 40 g sample treated according to the method.