Low Blank Preconcentration Technique for the Determination of Lead, Copper, and Cadmium in Small-Volume Seawater Samples by Isotope Dilution ICPMS (original) (raw)

1997, Analytical Chemistry

A simple low-blank method is described for the analysis of Pb, Cu, and Cd in seawater using Mg(OH) 2 coprecipitation and isotope dilution inductively coupled plasma mass spectrometry (ICPMS). Here, 20-40 µL of 9 M aqueous NH 3 is mixed into a 1.3 mL seawater sample spiked with enriched isotopes of Pb, Cu, and Cd. After centrifugation, the supernatant is discarded and the Mg-(OH) 2 precipitate dissolved in 100 µL of 5% HNO 3 for ICPMS analysis. This method is simple, accurate, and precise, with detection limits of Pb) 1.3 pM, Cu) 39 pM, and Cd) 5.0 pM and blanks of Pb) 0.62 pM, Cu) 27 pM, and Cd) 6.0 pM. The method is demonstrated by oceanographically consistent profiles of these trace metals at an ocean station in the eastern North Atlantic.