反相流动注射法测定啤酒中单宁的研究

反相流动注射法是一种快速、简便、精确，自动化操作的方法。在碱性（pH12的Na2B4O7-NaOH缓冲溶液）条件下，单宁能还原磷钨酸生成蓝色化合物在700nm有最大吸收峰。在最优的试验条件下，单宁浓度为0～10．0mg／L范围内峰高与浓度成线性关系，其线性相关系数为0．9996，方法检出限DL=16．8μg／L，精密度RSD=0．66％（n=12）。应用于实际啤酒样品中单宁的检测，加标回收率在99．25％－100．07％之间，具有较好的重现性和准确性；与标准分析方法比较，测定结果令人满意。

Determination of tannin in beer by reverse flow injection analysis

The reverse flow injection analysis method was rapid, simple, reliable and automatic. The method was based on the tannin deoxidization phosphotungstic acid to form blue compound in pH 12 alkaline solutions at the point of the maximum absorption peak of 700nm. Under the optimum analytical conditions,response to tannin concentration was linear in the range of 0-10.0mg/L. The correlation coefficient was 0.9996. The detection limit was 16.8μg/L. The relative standard deviation was 0.66% for 10mg/L tannin （n=12）.The proposed method was applied to the determination of tannin in beer successfully. The recovery was between 99.25% and 100.07%. The results of analysis were satisfactory compared with national standard method.