Colorimetric method for the determination of ethanol by Flow Injection Analysis

An automated Flow Injection Analysis system using stop-flow technique for quantifying ethanol based in a colorimetric detection method was developed. The system permitted analysis in a linear range of 0.05-1 g ethanol l(-1) without external dilution, a sampling frequency of 15 analyses per hour, and a relative standard deviation of 3.5%. A dilution line was implemented in the FIA system permitting the extension of the linear range to 0.5-5.2 g ethanol l(-1) maintaining the same sampling frequency and standard deviation. The system was applied to measure ethanol concentrations present in samples of an alcoholic fermentation and the results showed no significant difference with other analytical procedures (GC).