DETERMINATION OF TRACE-METALS IN SEA-WATER AND THE ONLINE REMOVAL OF MATRIX INTERFERENCES BY FLOW-INJECTION WITH INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRIC DETECTION

A flow injection inductively coupled plasma mass spectrometry method with matrix elimination for the determination of trace metals such as manganese, cobalt, copper, zinc and lead in sea-water is described. The method involves chelation of the analytes onto an iminodiacetate-based resin (Dionex Metpac CC-1) in a micro-column with the simultaneous matrix removal of indirectly interfering species such as sodium and chloride ions. The analytes are then eluted with 2.0 mol l-1 nitric acid. The procedure was validated by analysing Open Ocean (NASS-3), Coastal (CASS-2) and Estuarine (SLEW-1) certified reference materials using standard additions. Good agreement with the certified values was achieved for Cu, Zn and Pb in NASS-3 and CASS-2, and for Mn, Co, Cu and Zn in SLEW-1 using the multi-element time resolved software on the ICP-MS instrument. Recoveries were 97-105% and the precision at the 0.1 mug l-1 level was in the range 2.3-6.9% RSD (n = 3) for Mn, Cu, Zn and Pb in NASS-3.