Development of sensitive determination method for platinum in geological materials by carbon slurry sampling graphite furnace atomic absorption spectrometry

• Slurry sampling GFAAS for Pt determination in geological samples is proposed.
• The amphoteric AC is recommended as the enrichment agent for Pt(IV) adsorption.
• Great adsorption capacity and selectivity for studied system were reached.
• Low LOD was obtained for Pt determination in geological materials.
• XPS proved the surface reduction as one of the main adsorption mechanisms on AC.

A simple and cost effective preconcentration method based on modified activated carbon is proposed for the determination of traces of platinum (Pt) in geological samples by the carbon slurry sampling technique for graphite furnace atomic absorption spectrometry (GFAAS). The basic parameters affecting the adsorption capacity of Pt(IV) ions on modified activated carbon were studied and the effect of activated carbon modification has been determined by studying the initial runs of adsorption isotherms. The influence of chlorides and nitrates on adsorption ability of Pt(IV) ions onto the modified activated carbon for diluted aqueous solution was also studied in detail in respect to the determination of platinum in solid materials following digestion steps as outlined in the analytical procedure, which usually involves the application of aqua regia. The XPS studies confirmed that not only the surface reduction of Pt(IV) ions into Pt(II) is the main platinum adsorption mechanism on the activated carbon. Determination of platinum after its preconcentration on the modified activated carbon was tested and validated by applying certified reference materials. The proposed method has been successfully applied for the determination of Pt in real samples using the standard calibration method.