A study of the direct determination of Cd, Cr, Cu, Pb and Zn in certified reference materials of soils by solid sampling electrothermal atomic absorption spectrometry

A simple and rapid method for the direct determination of Cd, Cr, Cu, Pb and Zn in soil was developed. The method was developed using three certified reference materials of soil: Eutric Cambisol, Orthic Luvisols and Rendzina, which differed in their matrix composition. Chemical modifiers were essential to achieve reproducible and interference-free signals for the analytes studied. The best results were obtained with a Pd/Mg(NO3)(2) admixture for the determination of Cd, Pb and Zn and NH4F for Cu. The combination of W (as a permanent modifier) and Mg(NO3)(2) provided well-defined signal profiles for Cr. The following spectral lines were used: Cd 228.8 nm, Cr 520.6 nm, Cu 218.2 nm, Pb 205.3 nm and Zn 307.6 nm. The limit of detection was 4.2 ng g(-1) for Cd, 1.1 mu g g(-1) for Cr, 0.5 mu g g(-1) for Cu, 1.3 mu g g for Pb and 8.6 mu g g(-1) for Zn for the maximum sample mass used. Under optimized conditions, the analyte and matrix were separated effectively in situ, and aqueous standards could be used for calibration. (C) 2010 Elsevier B.V. All rights reserved.