Lacorn Markus, Hektor Thomas
R-Biopharm AG, An der neuen Bergstrasse 17, D-64297 Darmstadt, Germany.
J AOAC Int. 2018 Jul 1;101(4):1101-1111. doi: 10.5740/jaoacint.17-0466. Epub 2018 Apr 4.
EnzytecTM Liquid Ethanol is an enzymatic test for the determination of ethanol in kombucha, juices, and alcohol-free beer. The kit contains two components in a ready-to-use format. Quantification is based on the catalytic activity of alcohol dehydrogenase, which oxidizes ethanol to acetaldehyde and converts NAD+ to NADH. Measurement is performed in 3 mL cuvettes at 340 nm within 20 min. Samples with alcohol contents around 0.5% alcohol by volume need to be diluted 1:20 or 1:50 with water before measurement. Acetaldehyde interferes at concentrations higher than 3000 mg/L, whereas sulfite interferes at concentrations higher than 300 mg/L. The linear measurement range is from 0.03 up to 0.5 g/L ethanol, whereas LOD and LOQ are 1.9 and 3.3 mg/L ethanol, respectively. Kombucha with concentrations between 2.85 and 5.82 g/L showed relative repeatability standard deviation around 1%, whereas juices were below 2%. Results from a reproducibility experiment revealed that at a concentration of 0.1 g/L, the RSDR was at 2.5%, whereas at higher concentrations between 0.2 and 0.3 g/L, coefficients around 1% were obtained. Trueness was checked by using Cerilliant aqueous ethanol solutions and beer with concentration of 0.4 and 4 g/L (BCR-651 and BCR-652). Spiking of kombucha and juice samples resulted in recoveries between 95% and 104%. Acceptable stability was found for the whole test kit under accelerated conditions at 37°C for 2 weeks. The kit is also not susceptible to short freezing-thawing cycles and harsh transport conditions.
EnzytecTM 液体乙醇检测试剂盒是一种用于测定康普茶、果汁和无醇啤酒中乙醇含量的酶促检测方法。该试剂盒包含两个即用型组件。定量分析基于乙醇脱氢酶的催化活性，该酶将乙醇氧化为乙醛，并将 NAD+ 转化为 NADH。测量在 3 mL 比色皿中于 340 nm 波长下 20 分钟内进行。酒精含量约为 0.5%（体积分数）的样品在测量前需用水按 1:20 或 1:50 稀释。乙醛在浓度高于 3000 mg/L 时产生干扰，而亚硫酸盐在浓度高于 300 mg/L 时产生干扰。线性测量范围为 0.03 至 0.5 g/L 乙醇，而乙醇的检测限（LOD）和定量限（LOQ）分别为 1.9 和 3.3 mg/L。浓度在 2.85 至 5.82 g/L 之间的康普茶的相对重复性标准偏差约为 1%，而果汁的相对重复性标准偏差低于 2%。重现性实验结果表明，在浓度为 0.1 g/L 时，相对标准偏差（RSDR）为 2.5%，而在 0.2 至 0.3 g/L 的较高浓度下，系数约为 1%。通过使用浓度为 0.4 和 4 g/L 的 Cerilliant 乙醇水溶液以及啤酒（BCR - 651 和 BCR - 652）来检查准确性。向康普茶和果汁样品中加标后回收率在 95% 至 104% 之间。在 37°C 加速条件下放置 2 周，整个检测试剂盒具有可接受的稳定性。该试剂盒也不易受短期冻融循环和恶劣运输条件的影响。
