Ultratrace determination of cadmium by atomic absorption spectrometry using hydride generation with in situ preconcentration in a palladium-coated graphite atomizer

A very sensitive ETAAS method, with in situ trapping of the metal, is described for ultratrace determinations of Cd in liquid solutions. It is based on volatile Cd HG from a vesicular solution with subsequent trapping of the metal in a graphite platform coated with Pd. This Pd coating, on a pyrolytic graphite L'vov platform, acts as the atomizer, Sodium tetrahydroborate(nr) in a vesicular medium of didodecyldimethylammonium bromide is used to generate Cd hydride from the sample solution, This volatile species is trapped by the Pd coating, pre-heated at 150 degrees C, the preconcentrated Cd then atomized at 1600 degrees C and the transient AAS signal measured, Detection limits (DL) observed are in the ng l(-1) range (e.g., using a 1.4 ml Cd sample volume for preconcentration the DL was 60 ng l(-1)). Higher preconcentrations up to a maximum of 1.4 ng of total Cd deposited are possible with the proposed methodology, The RSD for ten replicate analyses of 1.4 mi of 500 ng l(-1) Cd solution (0.7 ng of total Cd) was 1.7%. The combination of vesicles-mediated HG with the ease of decomposition of Cd hydride on the Pd coating at 150 degrees C, provides a convenient Cd preconcentration method for enhancing the sensitivity of direct determinations of Cd by conventional ETAAS or by HGAAS.