USE OF EMULSION SYSTEMS FOR THE DETERMINATION OF SULFUR, NICKEL AND VANADIUM IN HEAVY CRUDE-OIL SAMPLES BY INDUCTIVELY-COUPLED PLASMA-ATOMIC EMISSION-SPECTROMETRY

A useful and rapid procedure is described for the determination of sul fur, nickel and vanadium in crude oil by inductively coupled plasma at omic emission spectrometry. Samples were prepared by emulsifying crude oil in water. Aqueous inorganic solutions with the same amount of emu lsifier and solvent were used as calibration standards, Heavy crude oi ls were analysed and the results were compared with those obtained by digestion methods. To evaluate the accuracy of the method, National In stitute of Standards and Technology Standard Reference Materials, 1622 c Sulfur in Residual Fuel Oil and 1634a Trace Elements in Fuel Oil, we re analysed. No statistically significant differences were observed be tween the results obtained by this method and the certified values. Th e precision of the method was in the range from 1 to 3% relative stand ard deviation.