DETERMINATION OF CADMIUM IN DIGESTED SOILS AND SEDIMENTS, RESP IN SOIL AND SEDIMENT EXTRACTS BY MEANS OF FLAMELESS ATOMIC-ABSORPTION WITH ZIRCONIUM COATED GRAPHITE TUBES

Cadmium is enriched by an extraction with APDC/MIBK and subsequent reextraction with nitric acid. A procedure is described for analyzing these solutions directly by means of flameless atomic absorption, inspite of the high concentration of nitric acid in a zirconium coated graphite tube. These tubes, proved to be very resistant (150-300 analyses). After treatment of the tubes with a Fe3+-solution no interference by accompanying anions and cations could be observed. By the extraction and reextraction procedure described cadmium is enriched by a factor of five. Samples of higher cadmium concentrations were analyzed by means of flame atomic absorption after the same sample preparation. Working conditions for flameless and flame atomic absorption are given. Detection limits have been calculated as 0.53 μg Cd/l in the case of flameless, 19.4 μg Cd/l in the case of flame atomic absorption. These values are further decreased by the above enrichment procedure to 0.1 and 4 μg Cd/l, respectively. © 1979 Springer-Verlag.