USE OF FLOW-INJECTION COLD VAPOR GENERATION AND PRECONCENTRATION ON SILICA FUNCTIONALIZED WITH METHYLTHIOSALICYLATE FOR THE DETERMINATION OF MERCURY IN BIOLOGICAL SAMPLES AND SEA-WATER BY INDUCTIVELY-COUPLED PLASMA-ATOMIC EMISSION-SPECTROMETRY

A novel and expeditious approach to the direct determination of mercur y in sea-water and biological samples based on a separation-preconcent ration system coupled on-line to a flow injection (FI) manifold is des cribed. The method employs on-line preconcentration of mercury on a 3 cm x 3 mm column packed with silica gel functionalized with methylthio salicylate (TS-gel) and placed in the injection valve of the FI manifo ld. Synthesis of the resin is simpler and faster than that of other re sins described previously, where many steps are required. In this syst em the metal was eluted from the column with thiourea and mixed on-lin e with NaBH4; mercury vapour was generated directly and separated via a gas-liquid separator. Various parameters and chemical variables affe cting the preconcentration of Hg-II, the direct generation of mercury vapour and the final determination by ICP-AES were evaluated. The cali bration graph was linear over the range 5-1000 ng ml(-1) Hg-II, with a relative standard deviation at the 10 ng ml(-1) level of 2.1%. The ac curacy of the method was evaluated by the analysis of certified refere nce materials. The results showed good agreement with the certified va lues.