Energy dispersive x-ray fluorescence spectrometric determination of trace elements in oil samples

A method is described for the determination of trace elements in petroleum by energy dispersive x-ray fluorescence spectrometry. Minimum sample preparation is required. This is achieved by making small targets and spiking the sample with a solution of Cr and Rh in H/sub 2/SO/sub 4/ or organo-Rh in mineral oil. Use of two spiking elements with different x-ray energies facilitates the determination of x-ray absorption corrections. In the NBS fuel oil (SRM 1634), V, Fe, Ni, and Mo were detected and the results of the analyses correspond well with the NBS certified values. In the shale oil, Fe, Ni, Zn, As, and Se were detected. The one-element spiking method works well for samples of low viscosity where the sample can be spread on the supporting foil thin enough so that the absorption of measured x-rays can be ignored, whereas the two-element spike is needed for high viscosity samples (NBS fuel oil) where samples cannot be made thin enough to ignore sample absorption.