Direct Determination of Tetraethyllead and Tetramethyllead in Gasoline by High-Performance Liquid Chromatography with Electrochemical Detection at Mercury Electrodes

Tetramethyllead and tetraethyllead are highly toxic compounds used as antiknock additives In gasoline. In this work, direct Infection of 1-to 10-μL samples of aviation and motor gasolines onto a C₁₈ reverse-phase HPLC column followed by electrochemical detection at a mercury electrode with acetonitrile (0.05 M tetraethylammonlum perchlorate) as the eluent provides a specific and sensitive method for determination of tetraalkyllead compounds via direct calibration. The redox process at mercury electrodes employed for detection Involves oxidation of the electrode and exchange of alkyl groups. This unique reaction occurs at much lower potentials than the direct oxidation at solid electrodes. The complex matrix in gasolines precludes the determination of tetra-alkyllead compounds using oxidation at a glassy carbon or other Inert solid electrode detectors.