定量核磁共振氢谱测定发酵饮料中乙醇、乙酸的含量

Determination of ethanol and acetic acid in fermented drinks by q^(1)H-NMR

以乙醇、乙酸为研究对象,采用定量核磁共振氢谱技术测定发酵饮料中乙醇、乙酸的含量。使用氘代二甲基亚砜为溶剂,3-(三甲基甲硅烷基)丙酸-d_(4)钠[sodium 3-(trimethylsilyl)propionate-2,2,3,3-d_(4),TMSP]为内标,90°脉冲,扫描次数(NS)为16,弛豫时间(D_(1))为20 s,采样时间(AQ)为4.50 s,298 K恒温测试。以乙醇(1.10 ppm)、乙酸(1.80 ppm)及TMSP(0.00 ppm)峰为定量峰,对5种发酵饮料中乙醇、乙酸的含量进行测定。q^(1)H-NMR测定乙醇线性范围为64.05~0.32 mg/mL,回收率99.68%~100.65%;乙酸线性范围为19.51~0.20 mg/mL,回收率98.38%~99.24%;乙醇、乙酸重复性相对标准差分别为0.11%、0.99%(n=6),48 h内测试结果准确可信。q^(1)H-NMR技术可用于发酵饮料中乙醇、乙酸的含量测定,该方法操作高效简便、不损耗样品,检测结果准确可靠,拓宽了醇、酸类成分的检测手段。

A quantitative analysis using q^(1)H-NMR was developed for the determination of ethanol and acetic acid in fermented drinks.The NMR experimental conditions were as follows:using DMSO-d 6 as solvent,TMSP as internal standard,90°pulse,scanning times NS(16),relaxation time D_(1)(20 s),sampling time AQ(4.5 s),constant temperature test at 298 K.Using ethanol(1.10 ppm),acetate acid(1.80 ppm)and TMSP(0.00 ppm)peaks as quantitative peaks,the content of ethanol and acetic acid in five fermented drinks were determined.The linear range and recovery rate of ethanol was 64.05-0.32 mg/mL and 99.68%-100.65%,and those for acetate acid was 19.51-0.20 mg/mL and 98.38%-99.24%.The repeatability RSD of ethanol and acetic acid were 0.11%and 0.99%(n=6),respectively,and the test results were accurate and reliable within 48 hours.The high universality,accuracy,reproducibility,and efficiency of the q^(1)H-NMR method demonstrated in this work suggest that this method could serve as a highly potential quantification alternative for quality assessment of alcohols and acids.