The Determination of Sulfur and Chlorine in Used Oil by X-Ray Fluorescence, ICP and Ion Chromatography

Abstract

Methods for the determination of total sulfur and chlorine in used oil were evaluated and compared using actual waste oil samples. Oxygen bomb combustion was followed by either ion chromatographic determination of sulfate and chloride or determination of sulfur by inductively coupled plasma (ICP) optical emission spectroscopy. Total sulfur and chlorine were determined by X-ray fluorescence (XRF) spectroscopy in samples prepared by fivefold dilution in mineral spirits. Oxygen bomb combustion and XRF gave results with good precision, and, by comparison with each other, very little bias. Problems with the settling of particulates in the XRF analyses were largely overcome by using a thin layer method for sample presentation to the spectrometer. Due to the presence of particulates and emulsified water, the determination of sulfur and chlorine in used oil is more difficult than in pristine oil. Bomb combustion, when followed by IC or ICP, and XRF have been shown to be satisfactory analytical methods for determining total sulfur and chlorine in used or waste oil. 12 refs., 1 fig., 3 tabs.