Different chromatographic methods for simultaneous determination of diloxanide furoate, metronidazole and its toxic impurity

TLC densitometric and RP-HPLC methods are innovative chromatographic methods used for determination of diloxanide furoate, metronidazole and its impurity, 4-nitroimidazole. In the developed TLC densitometric method, appropriate separation was achieved using silica gel 60 F254 TLC plates and ethyl acetate/acetone/hexane/ammonia solution (9.5:0.5:0.3:0.3, by volume), as a developing system and the separated bands were UV-scanned at 276 nm. While the developed RP-HPLC method depended on separation of components on C8 column using deionized water containing 0.05 % TEA: methanol (40:60, v/v) as a mobile phase at constant flow rate of 1 mL/min with UV detection at 276 nm. Variables affecting performance of the developed methods were studied and optimized. Regression analysis showed acceptable correlation coefficients in the selected ranges with excellent percentage recoveries. The methods showed no significant interferences from dosage form excipients, and the validity of the proposed methods was further assessed by applying standard addition technique. In addition, results obtained by applying the proposed methods were statistically compared to those obtained by applying the reported method and no significant difference was found between them. The suggested methods were successfully applied for the determination of the cited drugs in bulk powder, laboratory prepared mixtures and commercial tablets.