Determination of organometallic compounds in surface water and sediment samples with SPME-CGC-ICPMS

Organometal compounds of tin, mercury and lead were simultaneously determin ed in environmental, water and sediment samples by CGC-ICPMS. Instead of cl assical liquid/liquid extractions, solid phase microextraction was used as sampling technique. In this method, the organometallic compounds are in sit u derivatised in the aqueous phase and simultaneously extracted onto a poly dimethylsiloxane fiber, so that organic solvents are no longer necessary. T he sorbed organometals are subsequently released from the fiber in the GC i njection liner by thermal desorption. By sampling from the headspace, only the species of interest are sampled and no interfering matrix components ar e coextracted. With this new method, derivatisation, extraction, preconcent ration and injection into the GC takes only 10 min with a minimum of handli ng steps. Owing to the very low detection limits (0.13-3.7 ng/l as metal) o nly small sample amounts (25 ml of water, 0.5 g of sediment) are needed for one analysis. Finally, SPME is an inexpensive sampling technique that can be used with standard split/splitless injection systems.