Determination of various alcohols based on a new immobilized enzyme fluorescence capillary analysis

A novel method for the determination of ethanol in tequila based on the immobilized enzyme fluorescence capillary analysis (IE-EFCA) has been proposed. Alcohol dehydrogenase (ADH) was immobilized in inner surface of a capillary and an immobilized enzyme capillary bioreactor (IE-ECBR) was formed. After nicotinamide adenine dinucleotide (NAD+) as an oxidizer is mixed with alcohol sample solution, it was sucked into the IE-ECBR. The fluorescence intensity of the mixed solution in the IE-ECBR was detected at λex = 350 nm and λem = 459 nm. The experimental conditions are as follows: The reaction time is 20 min; temperature is 40 °C; the concentrations of phosphate buffer solution (pH 7.5) and NAD+ are 0.1 mol L−1 and 5 mmol L−1, respectively; immobilization concentration of ADH is 10 U L−1. The determination range of ethanol is 2.0–15.0 g L−1 (F = 10.44C + 6.6002, r > 0.9958); its detection limit is 1.11 g L−1; and relative standard deviation is 1.9%. IE-EFCA method is applicable for the determination of the samples containing alcohol in medicine, industry and environment.