THE EFFECT OF PALLADIUM MODIFIER ON THE EFFICIENCY OF ANTIMONY HYDRIDE TRAPPING IN GRAPHITE-FURNACE ATOMIC-ABSORPTION SPECTROMETRY (AAS)

The performance of palladium as permanent chemical modifier electropla ted on the surface of a graphite tube for the preconcentration of anti mony hydride was examined and compared with thermally formed Pd-coatin gs. The application of Pd-electroplated tubes allows to perform at lea st 75 determination cycles without any significant change in the effic iency of hydride collection. This is an advantage over the thermally f ormed palladium coating which must be obtained individually before eac h measurement. After the optimization of the system parameters a conce ntration detection limit of 48 ng/L and an absolute detection limit of 71 pg for a 1.48 mi, sample were obtained. The procedure was applied to the determination of antimony at a concentration level of 0.2 mu g/ L in a tap water sample.