A simple and validated RP-HPLC method for the estimation of methylcobalamin and Alphalipoic acid in soft gelatine capsule dosage form

Simple, precise, rapid and selective reverse phase high performance liquid chromatographic (RP‐HPLC) methods have been developed and validated for the assay determination of Methylcobalamin 1500 mcg and Alphalipoic acid 300 mg in soft gelatine capsule formulation. Two separate chromatographic conditions were used for estimation of Methylcobalamin[1] & Alphalipoic acid[2]. The methods use Phenomenox Luna (C‐18, 250 x 4.6 mm, 5 μm) column and gradient elution for both the methods. The aqueous mobile phase contained 0.02 M phosphate buffer adjusted to pH 3.5 with hexane-1-sulphonic acid, sodium salt as ion pairing reagent and acetonitrile for both the methods. Separation and quantification was achieved by changing the proportion of the system linearly with a time‐schedule programme. Detection was carried out in the range of 200 to 600 nm using photodiode array detector and set at 240 nm for alphalipoic acid and at 266 nm for Methylcobalamin and further analysis was carried out using a UV detector. These methods have been validated and found to be applicable in routine analysis for Methylcobalamin & Alphalipoic acid capsule. The precision is exemplified by relative standard deviations of 0.78% for Methylcobalamin and 0.53% for Alphalipoic acid. Good linearity was observed between the concentration of the analytes and peak area with correlation coefficients of 0.99995 and 0.99941 respectively. Mean recoveries obtained during spiking experiments were found to be 101.43 % and 99.43 % respectively
Author(s): Nandini R. Pai and Seema S. Sawant

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