Determination of lead in oil products by derivative potentiometric stripping analysis Original Research Article

A method for the determination of lead in oil products by derivative potentiometric stripping analysis is described. The only necessary sample pretreatment is the extraction of lead(II) from the corresponding alkyl derivatives by hot concentrated hydrochloric acid in a proper extractor. The metal ions are concentrated as the metal on a glassy carbon working electrode and then stripped by a suitable oxidant. Potential and time data are digitally converted into dt dE−1 and E is plotted vs. dt dE−1, thus increasing both sensitivity of the method and resolution of the analysis. Quantitative analysis is carried out by the method of standard additions. A good linearity was obtained in the range of concentrations examined. Recoveries of 96–98% were obtained from a virgin naphtha spiked at different levels. The detection limit is in the order of 10−8 mol l−1 and the reproducibility (mean 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.