Direct solid sample analysis of geological samples with SS-GF-AAS and use of 3D calibration

These results from direct solid-sample trace-element analysis, with 3D calibration, follow those of earlier publications. Cd, Cr, Cu, Ni, Pb, and Zn have been determined in complex inorganic powder samples, e.g. sediments, soils, rocks, and minerals. The measurements were performed with two SS-GF-AAS spectrometers which differ in the type of graphite furnace (transverse and longitudinal tube) and the background-correction technique (with and without the Zeeman system). The performance of the 3D calibration method was optimized by systematic investigation and the 2D- and 3D calibration techniques were compared. Another feature is the determination of confidence limits of the 3D calibration. This calibration error was calculated by the statistical bootstrap method. The results of calibration experiments and the precision and accuracy of the determination of trace elements in CRMs show that 3D calibration becomes increasingly essential as the refractory character of the analyte increases. Although there are large differences between the state of development and technical performance of the instruments used, 3D-calibration works with both SS-GF-AAS spectrometers.