Determination of mercury and thallium in seawater by electrothermal vaporization inductively coupled plasma mass spectrometry

Electrothermal vaporization inductively coupled plasma mass spectrometry (E TV-ICP-MS) has been applied to the determination of Hg and T1 in seawater s amp les. Various modifiers were tested for the best signal of these element s. After preliminary studies, 0.3% EDTA, 0.1% m/v TAC and 1% v/v HCl were a dded to the sample solution to work as the modifier. Since the sensitivitie s of Hg and T1 in various seawater matrices and aqueous standard solutions were quite different, standard addition method and isotope dilution method were used for the determination of Hg and T1 in these seawater samples. Thi s method was applied to the determination of Hg and T1 in NASS-4 and CASS-3 reference seawater samples and seawater samples collected from the Kaohsiu ng area. Results obtained by isotope dilution method and method of standard additions agreed satisfactorily. Detection limits were in the range of 5-1 5 and 0.4-0.5 ng l(-1) for Hg and T1 in seawater, respectively, with the ET V-ICP-MS method. The precision between sample replicates was better than 18 % for all the determinations.