Secondary ion mass spectrometry for characterizing antimony, arsenic and selenium on graphite surfaces modified with noble metals and used for hydride generation atomic absorption spectrometry

The surface and sub-surface distribution of noble metals (after electrodeposition of 600 μg or thermal reduction of 10 μg as modifiers), as well as Sb, As and Se (200 ng) as analytes after their deposition on the graphite surface was investigated using secondary ion mass spectrometry (SIMS) in the dynamic mode. This permitted simultaneous observation of the depth profile distribution of modifier and analyte with a depth resolution of down to approximately 25 nm, limited however, by the surface roughness of the samples. Hydride generation was intentionally used for this purpose because in this approach the investigated system: graphite-modifier with added analyte is free from matrix components. This was essential for the evaluation of this novel approach using SIMS for surface analysis. Investigations concerning the distribution of analytes were performed on the graphite surface modified with palladium, iridium or rhodium. It was found that after deposition at 400 deg. C, all analytes partially penetrated the graphite surface and their distribution overlaps the distribution pattern of the noble metals. The degree of penetration differs for each analyte and depends on the modifier used