Determination of organometallic forms of mercury, tin and lead by in situ derivatization, trapping and gas chromatography – atomic emission detection

Abstract

The development of a speciation method is described with the ultimate goal to simultaneously determine various organometallic forms of mercury, tin and lead at picogram concentration levels. The compounds are derivatized by ethylation (NaBEt 4) or hydride generation (NaBH 4), stripped with helium from solution and preconcentrated on Chromosorb at room temperature or at −160°C, respectively. The trapped species are released from the adsorbent by thermal desorption, separated by capillary gas chromatography, and detected by a microwave induced plasma atomic emission detector (MIP–AED). The influence of important process parameters, like stability/efficiency of the derivatizing agent, purge time and flow, and AED make up gas flow rate on signal intensity are discussed. Preliminary results prove a good reproducibility and recovery, and low detection limits (<1 ng/l) of this method.