Abstracto

Sensitive Titrimetric And Spectrophotometric Methods For The Assay Of Albendazole In Pharmaceuticals Using Sodium Periodate

K.Basavaiah, V.Ramakrishna, B.C.Somashekar, U.R.Anilkumar

Titrimetric and spectrophotometric methods, two each, are described for the assay of albendazole in bulk drug and in tablets using sodium periodate and two dyes, methyl orange and indigo carmine as reagents. In direct titrimetry (method A), albendazole solution is titrated directly with sodium periodate in HCl medium in the presence of potassium bromide to a methyl orange end point. In indirect titrimetry, (method B) an acidic solution of albendazole is treated with a measured excess of periodate in the presence of a large excess of bromide followed by iodometric determination of residual bromine. Spectrophotometric methods involve the addition of a known excess of periodate in acid medium and in the presence of excess of bromide followed by determination of residual bromine by reacting with fixed amount of either methyl orange and measuring the absorbance at 520 nm (method C) or indigo carmine and measuring the absorbance at 610 nm (method D). In all the methods, the amount of periodate reacted corresponds to the amount of albendazole. In both titrimetric methods, the reaction follows a 4:1 (albendazole:NaIO4) stoichiometry and the methods are applicable over 2-18 mg (method A) and 3-20 mg (method B) ranges. In spectrophotometric methods, the absorbance is found to increase linearly with concentration of albendazole which is corroborated by the correlation coefficients of 0.9989 and 0.9986 for method C and method D, respectively, The systems obey Beer’s law for 0.5-5.0 μg/ml (method C) and 2.5-25.0 μg/ml (method D). The calculated apparent molar absorptivity values are found to be 2.92×104 and 5.11×103 l/mol/cm for method C and method D, respectively, and the corresponding Sandell sensitivities are 0.0091 and 0.0052 μg/cm2. The limits of detection and quantification are reported for both spectrophotometric methods. Intra-day and inter-day precision and accuracy of the described methods were evaluated as per ICH guide lines. The methods were successfully applied to the assay of albendazole in tablets and the results were compared with those of a reference method by applying Student’s t-test and F- test. No interference was observed from common tablet adjuvants. The accuracy and reliability of the methods were further ascertained by performing recovery tests by standard addition method.