Determination of the concentration of ethanol in commercial gasoline using Raman spectroscopy

Abstract

Several techniques are currently employed to control the quality of fuels in order to identify possible anomalies in the products sold at the fuel stations, but they are expensive. The use of the Raman spectroscopy technique may replace complex, costly and time-consuming laboratory analysis techniques that rely on specialized labor. Raman spectroscopy is an easy-to-operate technique that is quick to obtain results and requires no reagents or sample preparation. In this work the results of the tests carried out on samples of commercial unleaded gasoline (called “type C” in Brazil) of stations of a specific vendor are demonstrated to determine the concentration of anhydrous ethanol and verify if the samples comply with the regulations of the National Agency of Petroleum, Natural Gas and Biofuels (ANP) (27% of anhydrous ethanol). All samples analyzed met the regulation (percentage £ 27% of anhydrous ethanol). In the Raman technique, the results are presented in a fast and objective way, allowing that the foci of nonconformity to be determined and punctual inspection actions to be effective to meet fuel specifications and guarantee consumer satisfaction.

Keywords: Raman spectroscopy. Quality control. Gasoline. Ethanol. Methods of analysis. Conformity of fuels.