低场核磁共振波谱仪快速测定饮料酒中酒精度

Rapid determination of alcohol content in alcoholic beverages by low-field NMR

基于低场台式核磁共振波谱仪,采用一维核磁共振氢谱(^(1)H nuclear magnetic resonance,^(1)H NMR)技术,建立了快速测定饮料酒(白酒、啤酒、葡萄酒和樱桃发酵酒)中酒精度的标曲法、内标法和外标法。方法检出限和定量限分别为0.08%和0.26%(体积分数)。在体积分数0.5%~80%时,标曲法、外标法和内标法的线性相关系数R^(2)分别为0.9961、0.9961和0.9995。3种方法的日内和日间精密度均小于5%。标曲法、外标法和内标法的加标回收率分别为88.1%~97.81%、84.61%~107.36%和81.83%~111.91%。可见此方法线性、重现性、回收率等均能达到准确定量的要求。该文所建立的^(1)H NMR法与GB 5009.225—2016《食品安全国家标准酒中乙醇浓度的测定》中数字密度计法的测定结果误差±5%,满足方法可行性验证要求。相比国标法,样品无需复杂前处理、样品用量少(仅需500μL)、测样时间短(<5 min)。相对于高场核磁共振波谱仪,低场台式核磁共振波谱仪体积小、重量轻、便于移动,适合饮料酒中酒精度的快速和规模化分析。

Based on the low-field NMR,^(1)H NMR was used to establish the standard curve method,internal standard method,and external standard method for the rapid determination of alcohol content in Baijiu,beer,wine,and kirsch.The limits of detection and quantification were 0.08%(volume fraction) and 0.26%(volume fraction),respectively.Good linearity was observed in the alcohol content range of 0.5%-80%(volume fraction),with correlation coefficient R^(2) of the standard curve method,the external standard method,and the internal standard method being 0.996 1,0.996 1,and 0.999 5,respectively.The precisions(relative standard deviation,RSD) of the three methods were less than 5%.The methods had good reproducibility and accurate results.The spiked recoveries of the standard curve method,the external standard method,and the internal standard method were 88.1%-97.81%,84.61%-107.36%,and 81.83%-111.91%,respectively.It could be seen that the linearity,reproducibility and recovery of the methods met the requirements of accurate quantification.The errors between the methods of this study and the digital densimeter method of GB 5009.225—2016 were within ±5%,which met the requirements of feasibility comparative analysis and verification.Compared to the national standard method,the methods of this study had the advantages of simpler sample pretreatments,less sample usage(only 500 μL),and short test times(less than 5 min).Compared with the high-field NMR spectrum,the low-field NMR has the advantages of small volume,light weight and easy movement.It is suitable for the rapid and large-scale determination of alcohol content in alcoholic beverages.