Determination of trace elements in rainwater by total-reflection X-ray fluorescence

Three quasi-independent analytical procedures are presented. The three sample preparation techniques compared are direct analysis, preenrichment of the trace elements in rainwater by freeze-drying and redissolution in dilute nitric acid, and a matrix removal and preconcentration procedure by metal chelation, chromatographic adsorption of the metal complexes, and subsequent elution of the metal chelates prior to TXRF measurement. The elements determined are S, K, Ca, Tl, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Pb, Se, Rb, Sr, Mo, Cd, and Ba. Systematic investigations for the characterization of the analytical procedures with regard to blanks, detection limits, precision, and accuracy are described and discussed. The accuracy was checked by independent analyses of duplicate samples using differential pulse anodic stripping voltammetry. (orig./PW)