Chemkistry Research Center, University of Shahid Beheshti, Tehran, I.R. Iran
A combined electrodeposition-ETAAS technique has been applied to the analysis of Pb, Cd, Co, Ni, Cr and Mn in biological samples in order to overcome interferences and to minimize sample pretreatment. It requires minimal sample preparation with the electrolysis process aiding partial decomposition of the organic matrix, adequate for the release and deposition of trace elements. In an initial electrodeposition step, the graphite furnace is coated by Pd. Analytes are then electrodeposited in situ from the sample at optimized applied voltage and time onto the Pd-coated furnace, followed by removal of spent electrolyte and atomization. The high background signals due to matrix components of urine and blood were eliminated by the technique and the sensitivity of determination was improved up to five-fold with respect to conventional ETAAS technique. A good precision of 1-3 %RSD (depending on the element and sample matrix) has been obtained. The recovery of added analytes is close to 100% based on comparison with conventional ETAAS of aqueous samples. The accuracy of the technique was established by analyzing the urine standard reference material, SRM2670. The results of determinations of the elements tested are within the range of certified values given by the NIST with an acceptable %RSD.