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 ind uctively coupled plasma mass spectrometry (USS-ETV-ID-ICP-MS) has been appl ied to the determination of Cd, Hg and Pb in coal fly ash samples. Thioacet amide (TAC) was used as the modifier. Since the sensitivities of the elemen ts 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 i n these coal fly ash samples. The isotope ratios of each element were calcu lated from the peak areas of each injection peak. This method has been appl ied to the determination of Cd, Hg and Pb in NIST SRM 1633a coal fly ash re ference material and a coal fly ash sample collected from Kaohsiung area. A nalysis results of reference sample NIST SRM 1633a coal fly ash agreed sati sfactorily with the certified values. The other sample determined by isotop e dilution and method of standard additions was agreed satisfactorily. Prec ision was better than 6% for most of the determinations and accuracy was be tter 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. (C) 1999 Elsevier Science B.V. Al l rights reserved.