DETERMINATION OF CADMIUM AND LEAD IN URINE BY ELECTROTHERMAL VAPORIZATION ISOTOPE-DILUTION INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY

Electrothermal vaporization isotope dilution inductively coupled plasm a mass spectrometry (ETV-ID-ICP-MS) was applied to the determination o f Cd and Pb in urine samples. The isotope ratios for each element in e ach analytical run were calculated from the peak areas of each isotope , A relatively low vaporization temperature was used, which separated the analyte from the major matrix components and improved the ion sign als of Cd and Pb significantly. Various chemical modifiers were tested to obtain the best signal of Cd and Pb, After preliminary studies, 1% HNO3 was added to the samples as the chemical modifier. The ETV-ID-IC P-MS method was applied to the determination of Cd and Ph in freeze-dr ied urine reference material MST SRM 2670 and several fresh urine samp les. The results for NIST SRM 2670 agreed satisfactorily with the cert ified values. The results for other samples obtained by isotope diluti on and the method of standard additions agreed satisfactorily, The det ection limits were 0.02 and 0.005 ng ml(-1) for Cd and Pb, respectivel y. The precision between sample replicates was better than 11% far all determinations.