1991 Volume 40 Issue 8 Pages 401-405
In an aqueous solution buffered at pH 8, Bromocresol Purple reacts with a quaternary ammonium ion containing a long-chain alkyl group to change color from blue to light yellow. This color change, however, is inhibited in the presence of alcohols such as methanol, ethanol, propanol and butanol. This phenomenon was used to determine ethanol content in aqueous solutions. The calibration curve obtained by the batchwise manual method was not a straight line. In the FIA method, a linear relationship between the peak heights and the ethanol concentrations was obtained up to 60 v/v% of ethanol, and the relative standard deviations were 1.5 and 0.2% for the determinations (n = 5) of 4 and 20 v/v % of ethanol, respectively. FIA made it possible to analyze about 35 samples per hour. This proposed method can be used as a rapid and simple method for the determination of ethanol content in alcoholic liquors.
