DETERMINATION OF LEAD IN GASOLINES BY DIFFERENTIAL PULSE POLAROGRAPHY AND DIFFERENTIAL PULSE ANODIC-STRIPPING VOLTAMMETRY

The article describes the determination of lead in gasolines by differential pulse polarography and differential pulse anodic stripping voltammetry. The method is based on the decomposition of tetraethyl-lead with a solution of ICl in acetic acid, elimination of the excess of iodine with a solution of styrene, extraction of lead with a 0.1 mol.l-1 HClO4 solution, conversion of the (C2H5)3Pb+ and (C2H5)2Pb2+ ions to Pb2+ ions on boiling, and subsequent measurement of the solution formed using the DPP technique, or, after elimination of the rest of the iodide ions, using the DPASV technique. The total duration of the analysis is 15-20 min in the first case and about 50-60 min in the second. The detection limit for the direct measurement of the extract with the DPP method is about 2 mg.l-1 of lead in the gasoline, and for the DPASV method it is 0.0001 mg.l-1.