Visual chemo-chronometric assay for quantifying ethanol in alcoholic drinks by the colorimetric Belousov-Zhabotinsky oscillator

Abstract

A simple chemo-chronometric method utilizing the Belousov-Zhabotinsky (BZ) oscillating reaction for the efficient detection of ethanol in alcoholic beverages has been developed. This visual detecting strategy only required a smartphone, without implemented instrumental detection systems, to video a unique colorimetric alternating (red-to-blue) feature of the BZ solution system containing 0.50 M bromate, 0.12 M malonic acid, 0.03 M bromide, 0.10 M sulfuric acid, and 0.2 mM ferroin under the perturbation of ethanol. The RGB intensity signals, termed the colorimetric oscillating signals (COS), could be drawn from recorded files through the image processing. We found from the COS characteristics that the oscillation period was inversely proportional to the ethanol levels as a consequence of its reaction with bromate in the studied system. Based on the established calibration, the ethanol content was effectively evaluated with good precision (<2.8% RSD). Also, the assay was successful with 5% error for the quantification of ethanol in commercial drink samples, signifying its accuracy and potential applicability.