Departamento de Química, Fundação Universidade Regional de Blumenau, FURB, Campus 1, Rua Antônio da Veiga, 140, Victor Konder, 89012-900, Blumenau, SC, Brazil.
Departamento de Química, Fundação Universidade Regional de Blumenau, FURB, Campus 1, Rua Antônio da Veiga, 140, Victor Konder, 89012-900, Blumenau, SC, Brazil.
Talanta. 2022 May 1;241:123229. doi: 10.1016/j.talanta.2022.123229. Epub 2022 Jan 22.
A high-throughput method for the determination of ethanol in vodka and cachaça using 96-well-plate digital images was proposed and validated. The standard method consists of beverage distillation, measuring its density using a pycnometer, and converting it into ethanol content. It is simple, but it is time-consuming and susceptive to error. The proposed method exploits the suppression of phenolphthalein ionization by ethanol in an alkaline solution and the fading of the pink solution was converted into ethanol content. It consists in mixing 1 mL of sample with 0.1 mL of an alkaline phenolphthalein solution. 96-well-plate images were acquired using a desktop scanner. Red, green, and blue (RGB) values from the 96 wells were automatically extracted using ReadPlate (ImageJ plugin). Then, RGB values were exported to a spreadsheet that converted these values into analytical signals and calculated the ethanol content in beverages. The ethanol content of cachaças and vodkas was 33-45% (v/v) and it was also the linear range of the proposed method. The method's precision was evaluated using relative standard deviation (RSD). Five cachaças and three vodkas were analyzed. Each beverage was analyzed six times on the same day (intra-day repeatability) and three consecutive days (inter-day repeatability) by three different analysts (inter-analyst repeatability). The intra-day repeatability average was 1.7% (1.2-2.2% range), the intra-day repeatability average was 2.6% (1.9-3.5% range), and the inter-analyst repeatability average was 4% (2.6-6.2% range). Accuracy was evaluated by comparing the proposed method with the standard method using a percent error and a paired t-test. The average percent error was 1.9%, in the paired t-test, the p-value average value was 0.25. The proposed method can analyze 12 samples in 30 min, whereas the standard method spends around 1 h on each sample. Thus, the proposed method provides high-throughput compared with the standard method.
本文提出并验证了一种使用 96 孔板数字图像测定伏特加和甘蔗酒中乙醇的高通量方法。标准方法包括饮料蒸馏、使用比重瓶测量其密度以及将其转化为乙醇含量。该方法简单，但耗时且容易出错。所提出的方法利用了乙醇在碱性溶液中对酚酞离子化的抑制作用，以及粉红色溶液的褪色转化为乙醇含量。该方法包括将 1 mL 样品与 0.1 mL 碱性酚酞溶液混合。使用台式扫描仪获取 96 孔板图像。使用 ReadPlate（ImageJ 插件）自动提取 96 孔的红、绿、蓝（RGB）值。然后，将 RGB 值导出到电子表格中，该表格将这些值转换为分析信号并计算饮料中的乙醇含量。甘蔗酒和伏特加的乙醇含量为 33-45%（v/v），也是该方法的线性范围。使用相对标准偏差（RSD）评估方法的精密度。分析了五款甘蔗酒和三款伏特加。每种饮料在同一天（日内重复性）和连续三天（日间重复性）由三位不同的分析人员进行六次分析（分析人员间重复性）。日内重复性平均值为 1.7%（范围为 1.2-2.2%），日间重复性平均值为 2.6%（范围为 1.9-3.5%），分析人员间重复性平均值为 4%（范围为 2.6-6.2%）。通过比较百分比误差和配对 t 检验，使用标准方法评估准确性。平均百分比误差为 1.9%，在配对 t 检验中，p 值平均值为 0.25。与标准方法相比，该方法可在 30 分钟内分析 12 个样品，而标准方法每个样品耗时约 1 小时。因此，与标准方法相比，该方法提供了高通量分析。
