Development and validation of spectrophotometric, HPTLC and HPLC methods for the determination of Imipramine and Chlordiazepoxide in pharmaceutical dosage forms

Three reliable, rapid and selective methods have been developed and validated for the determination of imipramine and chlordiazepoxide in pharmaceutical dosage forms. The first method is spectrophotometric method includes simultaneous estimation method, first order derivative spectrophotometric method, isoabsorptive method and multiwavelength method. All variables affecting the reaction have been investigated and the conditions were optimized. The second method is based on separation of the cited drugs (imipramine Rf =0.45 and chlordiazepoxide Rf = 0.26) followed by densitometric measurement of the intact drug spots at 288 nm by HPTLC. The separation was carried on silica gel plates using toluene: ethyl acetate: ethanol: diethanolamine (70: 15: 4: 1 v/v/v/v) as a mobile phase. The linearity range was 4-10μg for chlordiazepoxide and 5-9μg for imipramine with mean accuracy 99.99+1.02%. The third method is accurate and sensitive stability-indicating HPLC method based on separation of imipramine and chlordiazepoxide on a reversed phase C18 column, using a mobile phase of methanol at temperature 27+2 °C and UV detection at 275nm in an overall analysis time of about 9 min., based on peak area. The results obtained were analyzed by statistically to assess that no significant difference between each of the three methods. The validation was performed according to ICH guidelines.