Kinetic determination of ethyl carbamate in sugarcane spirits exploiting digital videos

Kinetic methods are useful analytical methods, whose widespread application is often hindered by the need for strict time control. In this study, digital videos obtained using a smartphone camera were exploited for the first time for a kinetic enzymatic method. The inhibition of the acetylcholinesterase activity on the hydrolysis of acetylthiocholine to thiocholine was exploited for ethyl carbamate determination. This toxic and potentially carcinogenic contaminant must be controlled in beverages with a threshold limit of 210 μg L^-1 for sugarcane spirits. Ethyl carbamate binds to the active site of acetylcholinesterase in an alkaline medium (pH 8), thus diminishing the hydrolysis rate. Digital videos were recorded for 25 min, and analytical information (channel B, RGB color system) was extracted from frames taken every 10 s. The time required to achieve a reaction plateau, which is proportional to the analyte concentration, was used as the analytical parameter. Under the optimized conditions a linear response was observed for ethyl carbamate concentrations from 50 to 500 μg L^-1 (r² > 0.99) with a limit of detection of 15 μg L^-1 and a coefficient of variation of 3.2 % (n = 10). The proposed kinetic method is a cost-effective alternative for the determination of ethyl carbamate in sugarcane spirits, which compares favorably with other methods reported in the literature with regard to detectability and greenness (AGREE score of 0.77), while yielding results in agreement with the gas chromatography-mass spectrometry reference method.