以文多灵为对照品,溴酚蓝为显色剂,在pH 3.0缓冲溶液条件下于30 ℃显色5 min,用三氯甲烷萃取,于413 nm波长处采用离子对萃取分光光度法测定长春花中总生物碱的含量.结果表明:文多灵在0.04~0.28 g·L-1浓度范围内与吸光度呈线性关系,回归方程为Y=0.182 4 X-0.03,相关系数为0.999 3,文多灵的平均回收率为99.49%,总生物碱样品在10~50 min内测定稳定.经测定长春花的根、茎、叶、花、种子等不同部位中总生物碱含量分别为2.230%,0.411%,1.098%,0.503%和0.013%.

In a citric acid-phosphate buffer of pH 3.0,an ion-pair complex was formed between alkaloids in the sample and the color reagent bromophenol blue reacted at 30 ℃ for 5 min.The complex was extracted with CHCl3 in which the absorbance was measured at the wavelength of 413 nm.Pure vindoline (purity:>99%) was used as reference standard in the preparation of calibration curve.Linear relationship between the absorbance and concentration of vindoline was obtained in the range of 0.04-0.28 g·L-1,corresponding to the linear regression equation Y=0.182 4 X-0.03 (r=0.999 3).On the base of a known sample,different amounts of standard solution of vindoline were added separately to 8 portions of the sample solution to test for recovery of the method,the average value of recovery obtained was 99.49%.Total alkaloids in different parts of Catharanthus roseus were determined by the proposed method,giving results of 2.230% (in roots),0.411% (in stems),1.098% (in leaves),0.503% (in flowers) and 0.013% (in seeds).