Taha A M, Gomaa C S
J Pharm Sci. 1976 Jul;65(7):986-91. doi: 10.1002/jps.2600650709.
Binary mixtures of weak and strong UV-absorbing alkaloids were analyzed by a charge-transfer spectrophotometric method, utilizing iodine in ethylene dichloride as the acceptor. In the uncomplexed form, the strong absorbing alkaloid (papaverine, quinine, ergotamine, or reserpine) was measured at a wavelength where there was no interference from weak absorbers (at 335, 332, 315, or 300 nm, respectively). The weak absorbing alkaloid (ephedrine, codeine, atropine, or homatropine methylbromide) was determined by computing its contribution to the total charge-transfer band at 295 nm where absorbance was linearly additive for mixtures. The greater increase in the original epsilon-values of the weak absorbers upon complexation with iodine relative to the corresponding increase in the epsilon-values of the strong absorbers led to good recoveries even at the low dose ratios of the weakly absorbing, and often more potent, alkaloids.
采用电荷转移分光光度法，以二氯乙烷中的碘作为受体，对弱紫外吸收生物碱和强紫外吸收生物碱的二元混合物进行分析。在未络合形式下，强吸收生物碱（罂粟碱、奎宁、麦角胺或利血平）在无弱吸收剂干扰的波长下测定（分别为335、332、315或300 nm）。弱吸收生物碱（麻黄碱、可待因、阿托品或甲基溴东莨菪碱）通过计算其对295 nm处总电荷转移带的贡献来测定，在该波长下混合物的吸光度呈线性加和。与强吸收剂的ε值相应增加相比，弱吸收剂与碘络合后其原始ε值有更大的增加，这使得即使在弱吸收且通常更有效的生物碱低剂量比情况下也能实现良好的回收率。
