Determination of trace metals in seawater by ICP-MS after preconcentration and matrix separation by dithiocarbamate complexes

Abstract

A rapid single extraction procedure using dithiocarbamate complexing agent in methyl-isobutyl ketone (MIBK) organic phase and acid exchange back-extraction is described for the simultaneous quantitative preconcentration of Fe, Mn, V, Cr, Ni, Co, Cu, Zn, As, Mo, Cd, Pb and U in seawater followed by its determination by inductively coupled plasma mass spectrometry (ICP-MS). This method gives quantitative recoveries for all above metals at pH 4.1-6.4. A matrix matching seawater certified reference material (CRM), NASS-5, was used for calibration so as to minimize the matrix and other associated effects. Blanks and detection limits were in ng/l range. The method gives a recovery of 94-100% for 100 ml sample, facilitating the rapid and interference-free analysis of seawater samples. Excellent agreement was obtained with the certified values of another seawater CRM, CASS-4, when it was analyzed as an unknown. The major advantage of this procedure is that rapid analysis can be performed for a wide range of metals from relatively small samples.