Determination of cadmium,mercury and lead in coal fly ash by slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry

Ultrasonic slurry sampling electrothermal vaporization isotope dilution inductively coupled plasma mass spectrometry (USS-ETV-ID-ICP-MS) has been applied to the determination of Cd, Hg and Pb in coal fly ash samples. Thioacetamide (TAC) was used as the modifier. Since the sensitivities of the elements studied in coal fly ash slurry and aqueous solution were quite different, isotope dilution method was used for the determination of Cd, Hg and Pb in these coal fly ash samples. The isotope ratios of each element were calculated from the peak areas of each injection peak. This method has been applied to the determination of Cd, Hg and Pb in NIST SRM 1633a coal fly ash reference material and a coal fly ash sample collected from Kaohsiung area. Analysis results of reference sample NIST SRM 1633a coal fly ash agreed satisfactorily with the certified values. The other sample determined by isotope dilution and method of standard additions was agreed satisfactorily. Precision was better than 6% for most of the determinations and accuracy was better than 4% with the USS-ETV-ID-ICP-MS method. Detection limits estimated from standard addition curves were in the range of 24–58, 6–28 and 108–110 ng g^?1 for Cd, Hg and Pb, respectively.