茚三酮比色法测定青天葵中总游离氨基酸的含量

目的利用α-氨基酸与茚三酮反应产生颜色,产生的颜色可以使溶液的吸光度变化的原理,采用可见光分光光度法测定青天葵中总游离氨基酸的含量。方法以亮氨酸为标准品溶液,在568 nm波长下测定供试品溶液的吸光度,根据朗伯-比尔定律计算供试品中总游离氨基酸的含量。结果茚三酮比色法显色反应的最佳反应条件为加入缓冲液的pH值为5.0,用量为1.0 mL;显色剂用量为2.0 mL;反应温度和时间分别为100℃水浴加热19 min,冷却10 min。结论本方法准确、灵敏、重复性好,具有简便实用的特点。

Quantitative Determination of Total Free-Amino Acid in Nervilia fordii (Hance) Schltr. by Ninhydrin Colorimetric Method

Objective Based on the a-amino acids and ninhydrin color reaction principle, the ninhydrin colorimetry was used to determine quantitatively the amount of the free amino acids in Nervilia fordii （Hance） Schltr.. Methods The reference of leucine was defmed as the standard solution and absorbance was detected at 568 nm. The method focused on how to fred out and what was the optimal conditions for the color reaction which reflected the amout of the free amino acids calculated by lambert-beer law. Results The optimal coditions was as following as pH value of buffer solution used in the test was at 5.0 with the volume of 1.0 mL, the volume of reagent used in the test was of 2.0 mL, all the tests were performed at 100 ℃ water bath and lasted for 19 min, and then cooled for 10 min before the ninhydrin colorimetric test. Conclusion This method is accurate, sensitive and reproducible. It is charaterized by simplicity and practicability.