不同显色剂对牛膝总皂苷含量测定的影响

Effects of Different Chromogenic Agents on Determination of Content of Total Saponins From Achyranthis Bidentatae Radix

目的：考察不同显色方法对紫外-可见分光光度法测定牛膝总皂苷含量的影响。方法：采用紫外-可见分光光度法测定牛膝总皂苷含量，分别用5种方法进行显色，显色剂方法A为5％香草醛-冰乙酸：高氯酸：冰乙酸（2：8：50），方法B为5％香草醛-冰乙酸：高氯酸：乙酸乙酯（2：8：50），方法C为高氯酸，方法D为浓硫酸-甲醇（7：3），方法E为香草醛-浓硫酸（2：58）。以吸光度为指标，通过单因素试验考察显色时间和显色温度。结果：方法C和D在400～800nm处无最大吸收；方法E最大吸收波长544nm，但吸光度数值太小，不适合标准曲线测定；方法A和B均适合牛膝总皂苷含量的测定，最大吸收波长分别为（548±1），（554±1）nm，方法A峰型、加样回收率均优于方法B。显色时间15min，显色温度60℃。结论：方法A为牛膝总皂苷的最佳显色方法。

Objective： To investigate effects of different chromogenic agents on determining the content of total saponins from Achyranthis Bidentatae Radix by UV spectrophotometry. Method： Total saponins were determined by UV with five different chromogenic agents namely method A as 5% vanillin-glacial acetic acid： perchloric acid ： glacial acetic acid （2 ： 8 ： 50） , method B as 5% vanillin-glacial acetic acid ： perchloric acid ： ethyl acetate （2： 8： 50）, method C as perchloric acid, method D as sulfuric acid： methanol （7： 3）, method E as vanillin-sulfuric acid （2： 58）. With absorbance as index, chromogenic time and temperature was investigated by single factor tests. Result： Methdod C and D had not the maximuM absorption at 400-800 nm; The maximum absorption wavelength of method E was at 544 rim, but absorbance value was too small which was not suitable for determination of standard curve; The maximum absorption wavelengths of method A and B were at （548 ±1 ）, （554 ±1 ） nm, respectively, these two methods were suitable for determination of total saponins from Achyranthis Bidentatae Radix, whereas peak pattern and sample recovery of method A were better than method B. Conclusion： Method A was optimal chromogenic method of total saponins from Achyranthis Bidentatae Radix.