Determination of lead in oil products by derivative potentiometric stripping analysis

A method for the determination of lead in oil products by derivative potent iometric stripping analysis is described. The only necessary sample pretrea tment is the extraction of lead(II) from the corresponding alkyl derivative s by hot concentrated hydrochloric acid in a proper extractor. The metal io ns are concentrated as the metal on a glassy carbon working electrode and t hen stripped by a suitable oxidant. Potential and time data are digitally c onverted into dt dE(-1) and E is plotted vs. dt dE(-1), thus increasing bot h sensitivity of the method and resolution of the analysis. Quantitative an alysis is carried out by the method of standard additions. A good linearity was obtained in the range of concentrations examined. Recoveries of 96-989 6 were obtained from a virgin naphtha spiked at different levels. The detec tion limit is in the order of 10(-8) mol l(-1) and the reproducibility (mea n of 10 determinations) is 3.74%. Results obtained on commercial gasolines and virgin naphthas are not significantly different from those obtained by inductively coupled plasma atomic emission spectrometry and X-ray methods. (C) 1999 Elsevier Science B.V. All rights reserved.