Ž . Spectrochimica Acta Part B 54 1999 17551766 Double resonance laser-induced fluorescence of Cadmium and Zinc in the inductively coupled plasma and electrothermal atomizer M. Ezer, H.L. Pacquette, J.B. Simeonsson  Department of Chemistry, Uni  ersity of Iowa, Iowa City, IA 52242-1294, USA Received 28 May 1999; accepted 21 July 1999 Abstract Ž . Double resonance laser-induced fluorescence LIF spectrometry studies of Zn and Cd have been performed in the Ž . Ž . inductively coupled plasma ICP and electrothermal atomizer ETA . Stepwise excitation of Zn is accomplished at 213.856 nm and 636.235 nm with fluorescence emissions observed near 334.5 nm. Excitation of Cd is accomplished at 228.802 nm and 643.847 nm with fluorescence emissions observed near 361.1 nm and 347.6 nm. Calibration studies demonstrate that the double resonance LIF approaches provide high sensitivity and linearity over several orders of magnitude in both atomizers. Limits of detection for Zn and Cd in the ICP are 1.7 ngml and 5 ngml, respectively. Ž . Excellent sensitivity is observed in the ETA resulting in limits of detection of 70 pgml 700 fg absolute mass and 4 Ž . pgml 40 fg absolute mass for Zn and Cd, respectively. The Zn content of a bovine serum standard reference Ž . material NIST SRM 1598 has been determined by ETA-LIF and found to be 940 60 ngg, which is in very good agreement with the certified value of 890 60 ngg. Low-level ETA-LIF measurements of Zn in these studies are strongly limited by the high background level observed for this element.  1999 Elsevier Science B.V. All rights reserved. Keywords: Laser-induced fluorescence; Cadmium; Zinc; Inductively coupled plasma; Electrothermal atomizer 1. Introduction Ž . Cadmium Cd is one of the most hazardous elements to human health. It is present as a  Corresponding author. Fax: 1-319-353-1115. Ž contaminant in food leafy vegetables, grains, and . cereals , water, and tobacco leaves, as well as being a by-product of zinc and lead mining and smelting. The most dangerous characteristic of Cd is that it accumulates mostly in the liver and kidney and has a long biological half-life of 17  30  Ž . years in humans 1 . Zinc Zn has a dual role as a 0584-854799$ - see front matter  1999 Elsevier Science B.V. All rights reserved. Ž . PII: S 0 5 8 4 - 8 5 4 7 99 00102-0