苦木总生物碱含量测定的透射比浊法研究

Quantitative Determination of Total Alkaloids in Picrasma Quassioides by Transmission Turbidimetry

苦木是中国药典收载的常用中药材,生物碱类为其清热解毒功效的有效成分,但目前尚缺少标准的含量测定方法,严重制约该品种及相关制剂的质量控制.本文基于生物碱与改良碘化铋钾试液的络合沉淀反应,创新建立一种快速、简便的透射比浊定量分析方法,应用于苦木药材总生物碱含量测定.以苦木药材中丰度最高的生物碱成分苦木酮为对照,结合反应动力学研究,优化反应溶剂、介质酸度、反应时间等关键反应条件,确定在0. 1 mol/L盐酸水溶液中反应5～20 min,于500 nm处测定吸光度值,外标法计算试样中总生物碱含量.方法学验证结果表明,所建立的方法具有良好的线性和准确度,线性方程为A=5. 765 4C-0. 144 4(r=0. 998 4),平均回收率为92. 3%,相对标准偏差(RSD)为4. 5%(n=9).该方法应用于9批不同产地的苦木药材总生物碱含量测定,平均含量为5. 36 mg/g.为该品种的质量标准提供了科学依据.

Picrasma quassioides (D. Don) Benn., recorded in the Pharmacopeia of China, is commonly used in traditional Chinese medicine. Alkaloids of quassioides are the effective ingredient for heat-clearing and detoxication. However, at present, there is a lack of standard content determination method, which seriously impedes the quality control of this medicinal materials and related preparations. Based on the precipitation-complexometric reaction, in which complexes can be formed by alkaloids and modified bismuth potassium iodide solution, an accurate and rapid quantitative analysis method of transmission turbidimetry is established for the quantitative determination of total alkaloids in quassioides . Nigakinone, which is the most abundant alkaloids in quassioides , is used as reference control. Combined with the study of reaction kinetics, the key reaction conditions such as reaction solvent, medium acidity and reaction time are optimized. It is determined that 0.1 mol/L hydrochloric acid-water is used as the solvent, the reaction time is managed in 5-20 min, and the absorbance is detected at 500 nm. Thus the content of total alkaloids is calculated according to external standard method. The results of methodology validation elucidate that the established method has good accuracy and linearity, with a typical regression equation of A =5.765 4 C -0.144 4 (r =0.998 4), the average recovery of 92.3%, and the relative standard deviation (RSD) of 4.5%( n =9). The average content of total alkaloids in 9 batches of quassioides from different areas is 5.36 mg/g by using the present method,which provides scientific basis for the quality standard of quassioides .