Determination of tetraethyllead by solid phase microextraction–thermal desorption–quartz furnace atomic absorption spectrometry

Abstract

A new procedure that uses a preconcentration system based on solid phase microextraction (SPME) and detection by quartz furnace atomic absorption spectrometry after thermal desorption from the microextraction fiber has been proposed for the determination of tetraethyllead in gasoline (leaded and unleaded) and water. Three different volatilizators were designed and their influence in the thermal desorption of tetraethyllead was studied. Working tetraethyllead solutions were prepared in 40 ml amber vials and sampling was performed by exposing the SPME fiber to the headspace over vigorously stirred samples for 10 min. The analytical performance characteristics of the proposed procedure were as follows: the detection limit for tetraethyllead was 0.43 ng ml⁻¹, with a relative standard deviation of 6% for determination of 10 ng ml⁻¹ of tetraethyllead (n = 5) while the calibration curve was linear up to 50 ng ml⁻¹ range. The proposed procedure was finally applied to the determination of tetraethyllead in gasoline and water samples obtaining a good agreement with those values obtained by an alternative method that included the direct injection of tetraethyllead, via a septum, in the heated volatilizator with a gas chromatographic syringe, the tetraethyllead volatilisation and its transport by the gas carrier to the quartz furnace, where the analytical signal was observed. This procedure could be easily adapted for the speciation of ionic lead and tetraethyllead.