RUTHERFORD BACKSCATTERING SPECTROMETRY INVESTIGATION OF THE PERMEABILITY OF PYROLYTICALLY COATED GRAPHITE SUBSTRATES

Rutherford backscattering spectrometry (RES) and scanning electron mic roscopy (SEM) were used to investigate the interactions of analytes wi th pyrolytically coated graphite, which is typically used in graphite furnace atomic absorption spectrometry (GFAAS), Chemical species were found to migrate into the hulk of the graphite, up to depths of at lea st 3 mu m, when deposited in a solution form on a nontreated or an oxy gen-pretreated graphite flat. Because this migration was not observed when the analyte was deposited by vapor deposition or laser ablation, we conclude that the analyte migration proceeds via capillary action, as in the case of polycrystalline graphite, Pretreatment of the graphi te Bat with hydrogen prevented migration of the analytes into the bulk of the graphite when they were deposited in solution form.