Abstract
A new and practical method is proposed for the determination of ethanol in gasoline. It is based on ultrasonic assisted liquid-liquid microextraction (LLME) with hexane-water and a redox back- titration, in which ethanol is oxidized with potassium dichromate in excess, and later the remaining dichromate is titrated with ferrous ammonium sulfate. Detection of the end point of the titration was by potentiometry with a redox electrode. To estimate the accuracy of the method, fuel samples were fortified with ethanol at different concentrations, obtaining and average recovery of 99 ± 6 %. The precision of the method expressed as a relative standard deviation in percentage was of 5 %. Thus, an accurate and precise analytical method was developed, a practical and easy to implement tool in any laboratory.