微波消解—紫外分光光度法测定三叶青总游离氨基酸

Determination of total free-amino acid in Tetrastigmatis hemsleyani by microwave digestion-UV spectrophotometer

【目的】探索测定三叶青总游离氨基酸的最佳方法,为三叶青的综合开发与利用提供科学依据。【方法】以三叶青为原料、门冬氨酸为标准品,通过正交试验对微波消解提取三叶青总游离氨基酸的工艺条件进行优化,并利用紫外分光光度计测定其含量。【结果】影响微波消解法提取三叶青总游离氨基酸的因素顺序为：料液比〉提取温度=提取功率〉提取时间,其最佳工艺条件为：以蒸馏水为提取剂,在料液比1∶15、提取温度60℃、提取功率225 W的条件下提取20 min,用紫外分光光度法测得三叶青总游离氨基酸平均含量为0.678%。565 nm是门冬氨酸标准溶液和三叶青供试液的最佳测定波长;门冬氨酸质量浓度在0.001-0.014 mg/m L范围内与吸光值呈良好的线性关系（R2=0.9991）。【结论】微波消解—紫外分光光度法具有操作简单、溶剂用量少、提取时间短等优点,是测定三叶青总游离氨基酸含量的有效方法。

【Objective】The best method of determining the total free-amino acid in Tetrastigmatis hemsleyani was explored to provide the scientific evidence for its comprehensive development and utilization. 【Method】Tetrastigmatis hemsleyani was used as the material and aspartic acid as the standard. The microwave digestion extraction technology of total free-amino acid from Tetrastigmatis hemsleyani was optimized by orthogonal experiments, and its content was determined by UV spectrophotometer. 【Result 】The descending sequence of influencing microwave digestion extracting the total free-amino acid was material- liquid ratio, extracting temperature and extracting power, extracting time. The optimum extraction process was as follows： using distilled water as solvent, under 225 W and 60 ℃ for an extraction of20 min with the material-liquid ratio of 1∶15. Under the best processing condition, the average content total free-amino acid was 0.678%. The best wavelength to determine aspartic acid standard solution and the Tetrastigmatis hemsleyani test solution was 565 nm. Aspartic acid showed a better linearity and good correlation within a range of 0.001-0.014mg/m L, R2=0.9991. 【Conclusion】Microwave digestion-UV spectrophotometer is effective and simply operative with less solvent and shorter extraction time.