Pretreatment Based on Sulfhydryl Cotton Fiber Adsorption and Toluene Extraction for the Determination of Alkyl-Mercury Compounds in Aqueous Samples Using Capillary GC

A methodology of pretreatment for the determination of alkyl-mercury compounds in aqueous samples using capillary gas chromatography (GC) was described, which mainly comprised of sulfhydryl cotton fiber (SCF) adsorption/NaCl-HCl elution/toluene extraction. The factors with regard to the effect of adsorption were evaluated, which involved pH value and flow through SCF tube. The other factors affecting pretreatment were optimized, including eluent volume, elution time, extractant volume and shaking time. The extraction efficiency of alkyl-mercury from the eluent with toluene extraction was closer to 100% compared with benzene extraction. For methyl-mercury (ethyl-mercury), the detection limit was 0.58 ng/L (0.59 ng/L), the recovery 82.1-94.3% (87.9-101.7%) and the relative standard deviation 2.58-4.89% (3.19-5.04%).