Three new methods for the assay of albendazole using N-chlorosuccinimide

Two titrimetric and one spectrophotometric methods are described for the determination of albendazole in pure form and in formulations. In direct titrimetric procedure (Method A), the drug is titrated directly with N-chlorosuccinimide solution in hydrochloric acid medium using indigo carmine as indicator. In back titrimetry (Method B) the drug is treated with a measured excess of the oxidant in acetic acid medium followed by the determination of the residual oxidant iodometrically. Spectrophotometry (Method C), involves the addition of a known excess of N-chlorosuccinimide to albendazole in hydrochloric acid medium followed by the determination of surplus oxidant by oxidation and complexation reactions involving iron (II) and thiocyanate. The absorbance of the resulting orange-red colour was measured at 480 nm and related to albendazole concentration. Titrimetric assays are based on a 1:2 reaction stiochiometry between albendazole and N-chlorosuccinimide. Direct titrimetry is applicable over 2-13 mg range, and 4-14 mg of albendazole could be determined by back titration method. In spectrophotometry the regression analysis of Beer’s law plot showed a good correlation between 0.62-10.0 μg/mL albendazole with a correlation coefficient of -0.9964. The molar absorptivity and Sandell sensitivity were 4.14 x 10 L/moL/cm and 18. 82 ng/cm, respectively. The limits of detection and quantification, respectively, were 0.61 and 2.02 μg/mL. The proposed methods were applied successfully for the determination of albendazole in pharmaceutical formulations with mean recoveries of 97.36 to 102.36 per cent. The excipients present in formulations did not interfere. The accuracy and reliability of the methods were further established by parallel determination by the reference method, and by recovery studies.