A simple, precise and cost-effective determination of ethanol content in gasohol through the ferroin-catalyzed Belousov-Zhabotinsky oscillating system

Abstract

This work demonstrates precise and inexpensive methods for the determination of ethanol in gasohol samples based on its perturbation effect on the colorimetric oscillating pattern of the ferroin-catalyzed Belousov-Zhabotinsky (BZ) system. Without the requirement of any detection system, only a smartphone was employed to video an alternating red-to-blue color change of the BZ solution. The oscillation period, defined as the time interval between blue-to-blue solution color, can be drawn from a recorded video and employed as a key characteristic parameter. The results reveal that the oscillation period exponentially decreases with the increase of ethanol. The linear relation plotted between the logarithm of the oscillation period and the ethanol concentration is obtained. By using this linear calibration, the ethanol content can be efficiently quantified with good intra-day and inter-day precision (<2.75% RSD). Limits of detection and quantification of the method are 1.49% and 4.96%v/v, respectively. Combined with the liquid-liquid extraction (1:1 gasohol/water), our method is successfully applied for determination of the ethanol content in gasohol samples with satisfactory results (percentage error < 3.59%), reassured by the GC technique.