Determination of Diloxanide Furoate and Metronidazole in Binary Mixture Using First Derivative of the Ratio-Spectra and High-Performance Liquid Chromatography-UV Methods

Two methods are presented for simultaneous determination of diloxanide furoate and metronidazole. The first method depends on first derivative of the ratio-spectra by measurements of the amplitudes at 242.5 and 285.5 nm for diloxanide furoate and 225.5 and 300 nm for metrinidazole. Calibration graphs were established for 2-100 μg mL^-1 for diloxanide furoate and 1-50 μg mL^-1 for metronidazole. In the second method (HPLC), a reversed-phase column with a mobile phase of ethylacetate:chloroform:dioxin:methanol (8:7:2:3 (v/v/v/v)) at 0.9 mL min^-1 flow rate was used to separate both compounds with detection at 250-345 nm. Linearity was obtained in the concentration range of 0.025-50 μg mL^-1 for diloxanide furoate and 0.15-50 μg mL^-1 for metronidazole. All of the proposed methods have been extensively validated. These methods allow a number of cost and time saving benefits. The described methods can be readily utilized for analysis of pharmaceutical formulations. There was no significant difference between the performance of the proposed methods regarding the mean values and standard deviations. The described HPLC method showed to be appropriate for simultaneous determination of diloxanide furoate and metronidazole in pharmaceutical dosage forms and in hyman serum samples.