Determination of cadmium, mercury and lead in seawater by electrothermal vaporization isotope dilution inductively coupled plasma mass spectrometry

Electrothermal vaporization isotope dilution inductively coupled plasma mas s spectrometry (ETV-ID-ICP-MS) has been applied to the determination of Cd, Hg and Pb in seawater samples. The isotope ratios of the elements studied in each analytical run were calculated from the peak areas of each isotope. Various modifiers were tested for the best signal of these elements. After preliminary studies, 0.15% m/v TAC and 4% v/v HCl were added to the sample solution to work as the modifier. The ETV-ID-ICP-MS method has been applie d to the determination of Cd, Hg and Pb in NASS-4 and CASS-3 reference seaw ater samples and seawater samples collected from Kaohsiung area. The result s for reference sample NASS-4 and CASS-3 agreed satisfactorily with the ref erence values. Results for other samples determined by isotope dilution and method of standard additions agreed satisfactorily. Detection limits were approximately 0.002, 0.005 and 0.001 ng ml(-1) for Cd, Hg and Pb in seawate r, respectively, with the ETV-ICP-MS method. Precision between sample repli cates was better than 20% for most of the determinations. (C) 1999 Elsevier Science B.V. All rights reserved.