Determination of arsenic, cadmium, lead, antimony, selenium and thallium in coal fly ash using the stabilised temperature platform furnace and Zeeman-effect background correction

Abstract

Four decomposition procedures for coal fly ash samples were investigated for the subsequent determination of arsenic, cadmium, antimony, selenium, lead and thallium. Decomposition with nitric acid under pressure in a PTFE bomb or microwave oven was adequate for the determination of As and Se but resulted in low values for all the other elements. Decomposition with nitric, hydrofluoric and perchloric acids in a PTFE bomb could be utilised for As, Se, Cd, Pb and Tl determinations whereas Sb was partly lost under these conditions. Decomposition with nitric, hydrofluoric and hydrochloric acids in a microwave oven was applicable for all the elements and gave results that were in good agreement with the certified values. The stabilised temperature platform furnace (STPF) technique with Zeeman-effect background correction was used for the determination of all the elements. After decomposition of the samples, calibration graphs were constructed using aqueous standards; use of standard additions was unnecessary for all the elements when using a Pd-Mg(NO3)2 mixed modifier. The atomic absorption spectrometry (AAS) results for As, Sb and Se were compared with those obtained by neutron activation analysis (NAA).