采用光度法研究了电子给予体前列宁与电子接受体茜素之间的荷移反应,提出了荷移光度法测定前列宁含量的方法.在乙醇-水(7+3)混合溶液中,前列宁与茜素荷移络合物的最大吸收波长为546 nm,该络合物的组成比为1∶1,表观摩尔吸光率是3.82×103L·mol-1·cm-1.前列宁的质量浓度在70 mg·L-1范围内符合比耳定律.当前列宁的质量浓度为40 mg·L-1时,相对标准偏差(n=6)为1.0%.测定了前列宁片剂中前列宁的含量,并测得平均回收率为98.1%,所得值与片剂标示值和高效液相色谱法测定值相一致.

Photometic study on the charge transfer reaction between trimethoprim,the electron donor,and alizarin,the electron acceptor,was made,and based on this charge transfer reaction,a photometric method for determination of trimethoprim was proposed.In a mixed solution of ethanol and water (7+3),the charge transfer complex was formed between trimethoprim and allizatin with its absorption maximum at the wavelength 546 nm,and its mole ratio of 1 to 1.Apparent molar absorptivity (ε) was found to be 3.82×103L·mol-1·cm-1.Beer′s law was kept in the range within 70 mg·L-1.Precision of the method was tested at the concentration level of 40 mg·L-1 for 6 multiplicate determinations,and the value of RSD found was 1.0%.The proposed method was applied to the determination of trimethoprim in its tablets,giving results in consistency with the labeled value and with those found by HPLC.Recovery of the method was tested by standard addition method,and value of average recovery found was 98.1%.