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建立了非线性化学指纹图谱法测定啤酒中乙醇的方法。取4份5mL啤酒标样,分别加入0,1,2和4 mL 5%的乙醇,再分别加入20 mL 1 mol/L H2SO4、4 mL 1.25 mol/L丙二酸、3 mL 0.1 mol/L硫酸铈铵,以水定容至52 mL。在37.0℃,850 r/min反应条件下,恒速搅拌4 min,快速注入8 mL 0.8 mol/L NaBrO3,记录非线性化学指纹图谱。利用其最大波幅和乙醇含量拟合得出线性回归方程,用于测定其它啤酒中乙醇的含量。结果表明,在一定的浓度范围内,乙醇的浓度与最大波幅值线性关系良好,相关系数R为0.9989~0.9996,样品加标回收率为97.1%~102.0%,RSD为0.4%~1.7%。本方法快速、简便、重现性好、精密度高,是一种切实可行的测定啤酒乙醇含量的新方法,也可为复杂样品中其它成分的测定提供借鉴手段。
A method of non-linear chemical fingerprinting determination of ethanol in beer was established. Take 4 portions of 5 mL beer sample, add 0, 1, 2 and 4 mL of 5% ethanol respectively, add 20 mL 1 mol / L H2SO4, 4 mL 1.25 mol / L malonate, 3 mL 0.1 mol / L Ammonium cerium sulfate, water to volume 52 mL. Under the conditions of 37.0 ℃ and 850 r / min, the mixture was stirred at constant speed for 4 min, and then 8 mL 0.8 mol / L NaBrO3 was rapidly injected. The nonlinear chemical fingerprint was recorded. The linear regression equation was fitted using its maximum amplitude and ethanol content for the determination of ethanol content in other beers. The results showed that the concentration of ethanol had a good linear relationship with the maximum amplitude at a certain concentration range. The correlation coefficient R was 0.9989 ~ 0.9996. The spiked recoveries were 97.1% ~ 102.0% and RSD were 0.4% ~ 1.7%. The method is rapid, simple, reproducible and has high precision. It is a feasible and feasible method to determine the content of ethanol in beer and provides a reference for the determination of other components in complex samples.