DETERMINATION OF HYDROPHILIC THIOLS IN SEDIMENT POREWATER USING ION-PAIR LIQUID-CHROMATOGRAPHY COUPLED TO ELECTROCHEMICAL DETECTION

Twelve hydrophilic thiols in sediment porewater samples from the Chesapeake Bay were determined by reversed-phase high-performance liquid chromatography using trihaloacetate ion-pairing agents with amperometric detection at a mercury-film/gold electrode. The detection limit is about 2 pmol, and the precision is better than 3% at the 100-pmol level. Glassy carbon and bare gold electrodes were also examined but were found to have higher residual currents and were subject to more interferences than the mercury-film/gold electrode. The stability of thiols with respect to oxidation, in both standard solutions and samples, was also investigated under various conditions.