Determination of Ethanol in Gasoline by FT-IR Spectroscopy

Abstract

Ethanol is the primary oxygenate in gasoline in the United States. Gasoline containing various percentages of ethanol is readily available in the market place. A laboratory experiment has been developed in which the percentage of ethanol in hexanes can easily be determined using the O–H and alkane C–H absorptions in an infrared spectrum. Standard solutions of ethanol mixed with hexanes are prepared, and their infrared spectra collected. The areas under the O–H and C–H absorptions are used to prepare a standard curve, which is used to determine the percentage of ethanol. Results for the analysis of ethanol in gasoline from this model ethanol/hexanes calibration system compare favorably to advertised values, as well as to values determined by water extraction.