A rapid spectrophotometric method for quantitative determination of ethanol in fermentation products

Abstract

A rapid and accurate assay for monitoring ethanol production is required to control the progress of fermentation in various industrial-related research and processes. In this study, a spectrophotometric assay to measure ethanol concentration in fermentative samples was developed. Ethanol in unknown aqueous solution was extracted using tri-n-butyl phosphate (TBP) and subsequently oxidized by dichromate reagent. The oxidation product of ethanol with dichromate reagent could be visualized as blue green-color. The A595 values detected by spectrophotometer and ethanol concentration between 0.7%-8.0% were plotted in linear regression with high correlation coefficiency (R-2). In addition, The concentrations of methanol, propanol and butanol were determined as did in ethanol suggesting the broad application of this assay. Our established method was applied to commercial wine and fermentative products from yeast culture broths and the results were compared with Gas Chromatography Mass Spectrophotometry (GCMS) method. In this study, this assay was demonstrated as a cheap, rapid, and high accuracy method for determination of ethanol concentration in unknown solutions.