An instrument-free method based on visible chemical waves for quantifying the ethanol content in alcoholic beverages.

An alternative approach using visible chemical waves for ethanol determination is presented. The method is based on the dynamic change of chemical waves in the Belousov-Zhabotinsky (BZ) reaction by perturbation with ethanol. The observablepropagating waves, generatedina Petri dish, can be recorded by using a smartphone camera. The propagating distances are measured from photographic images and then plotted as a function of time to attain the wave velocity. It is found that wave velocities are inversely proportional to ethanol concentrations. By using this linear relationship, the ethanol content can be efficiently quantified with good intra-day and inter-day precision (<3% RSD). Validated by the GC technique, the developed method is highly reliable and successfully applied for quantifying the ethanol content in beer, colored whisky, and vodka samples. Hence, this new method provides an alternative practical strategy for simple quantitative detection of ethanol without the need for instruments.