Determination of trace elements in coal and coal fly ash by joint-use of ICP-AES and atomic absorption spectrometry

Microwave-acid digestion (MW-AD) followed by inductively coupled plasma-atomic emission spectrometry (ICP-AES), graphite furnace atomic absorption spectrometry (GFAAS), and hydride generation atomic absorption spectrometry (HGAAS) were examined for the determination of various elements in coal and coal fly ash (CFA). Eight certified reference materials (four coal samples and four CFA samples) were tested. The 10 elements (As, Be, Cd, Co, Cr, Mn, Ni, Pb, Sb, and Se), which are described in the Clean Air Act Amendments (CAAA), were especially considered. For coal, the HF-free MW-AD followed by ICP-AES was successful in the determination of various elements except for As, Be, Cd, Sb, and Se. These elements (except for Sb) were well-determined by use of GFAAS (Be and Cd) and HGAAS (As and Se). For CFA, the addition of HF in the digestion acid mixture was needed for the determination of elements, except for As, Sb, and Se, for which the HF-free MW-AD was applicable. The use of GFAAS (Be and Cd) or HGAAS (Sb and Se) resulted in the successful determination of the elements for which ICP-AES did not work well. The protocol for the determination of the 10 elements in coal and CFA by MW-AD followed by the joint-use of ICP-AES, GFAAS, and HGAAS was established.