The selective extraction of Cr(VI) in a cement matrix, based on treatment with 0.1 M Na2CO3 solution and subsequent determination of chromium by electrothermal atomic absorption spectrometry, was proposed. The method was applied to South African cement clinkers, natural gypsum, limestone and certified reference materials. The limit of detection of chromium determination in cement samples was found to be 0.14 microg/g. Between 30% and 80% of the total chromium in South African cement clinkers are Cr(VI) compounds and 8-26% of the total amount of Cr(VI) species is water soluble. The analytical performance of the proposed method was verified by the analysis of BCS-CRM, a sulphate-resisting Portland cement, and the results obtained agreed well with the certified values. The much higher values obtained for Cr(VI) in the basic environment resulting from Na2CO3 leaching more realistically illustrates the potential health hazards (dermatitis) to cement industry workers. 16 refs.
Primary author(s): Potgieter S S; Panichev N; Potgieter J H; Panicheva S