Direct determination of trace metals in seawater by electrothermal vaporization ICP-MS with Pd-HNO3 modifier

A method for the direct multi-element determination of As, Pb, Sb, Sn, and Tl in seawater by electrothermal vaporization-inductively coupled plasma ma ss spectrometry (ETV-ICP-MS) has been developed. IN situ separation of the salt matrix and the analytes was achieved by thermal pretreatment in the gr aphite furnace, prior to analyte vaporization. Palladium modifier was used to stabilize the analytes during thermal pretreatment; 5% (v/v) HNO3 was ad ded to remove chloride from the matrix, thus reducing isobaric interference of (ArCl)-Ar-40-Cl-35 on As-75. Calibration was achieved using matrix-matc hed standards prepared in a blank seawater matrix from which trace elements were removed by ion-exchange on silica-immobilized 8-hydroxyquinoline. Det ection limits in the range 0.015-0.042 mu g/L were obtained. Analyte spike recoveries were measured between 99 and 113%.