DETERMINATION OF TRACE-ELEMENTS IN HEAVY OIL SAMPLES BY GRAPHITE-FURNACE AND COLD VAPOR ATOMIC-ABSORPTION SPECTROMETRY AFTER ACID DIGESTION

A procedure was developed to determine the concentrations of trace ele ments (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 prepar ation was both repeatable and quantitative and allowed element determi nations by graphite furnace atomic absorption spectrometry (GFAAS) or cold vapour atomic absorption spectrometry (CVAAS) from the same sampl e solution. The detection limits were low, and low concentrations of a nalyte could be determined accurately. V and Ni were determined also b y inductively coupled plasma atomic emission spectrometry (ICP-AES), i n samples merely diluted with xylene (1:10), the ICP-AES results were in good agreement with the GFAAS results.