Determination of trace elements in heavy oil samples by graphite furnace and cold vapour atomic absorption spectrometry after acid digestion

A procedure was developed to determine the concentrations of trace elements (As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb and V) in heavy oil samples. The wet digestion (HNO3-H2SO4) method developed for the sample preparation was both repeatable and quantitative and allowed element determinations by graphite furnace atomic absorption spectrometry (GFAAS) or cold vapour atomic absorption spectrometry (CVAAS) from the same sample solution. The detection limits were low, and low concentrations of analyte could be determined accurately. V and Ni were determined also by inductively coupled plasma atomic emission spectrometry (ICP-AES), in samples merely diluted with xylene (1:10), the 1CP-AES results were in good agreement with the GFAAS results.