EDTA as the modifier for the determination of Cd, Hg and Pb in fish by slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry

Ultrasonic slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry (USS-ETV-ICP-MS) has been applied to the determina tion of Cd, Hg and Pb in several fish samples. The influences of the instru ment operating conditions and slurry preparation on the ion signals were re ported. In this study, a relatively low vaporization temperature was used w hich separated the analyte from the major matrix components and improved th e ion signals significantly. EDTA was used as the modifier to enhance the i on signals. Since the sensitivities of Cd, Hg and Pb in various fish slurri es and aqueous solution were quite different, the standard addition method and isotope dilution method were used for the determination of Cd, Hg and P b in these fish samples. This method has been applied to the determination of Cd, Hg and Pb in dogfish muscle reference material (DORM-2) and a swordf ish sample purchased from the market. The analysis results agreed with the certified values. The precision between sample replicates was better than 1 4% with the USS-ETV-ICP-MS method. Detection limits estimated from standard addition curves were about 3-6, 3-9 and 6-7 ng g(-1) for Cd, Hg and Pb, re spectively, in different samples.