Rutherford Backscattering Spectrometry Investigation of the Permeability of Pyrolytically Coated Graphite Substrates

Rutherford backscattering spectrometry (RBS) and scanning electron microscopy (SEM) were used to investigate the interactions of analytes with pyrolytically coated graphite, which is typically used in graphite furnace atomic absorption spectrometry (GFAAS). Chemical species were found to migrate into the bulk of the graphite, up to depths of at least 3 μm, when deposited in a solution form on a nontreated or an oxygen-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 graphite flat with hydrogen prevented migration of the analytes into the bulk of the graphite when they were deposited in solution form.