ABSTRACT
Three sensitive, accurate and precise HPLC methods were devolved for the simultaneous determination of vilazodone HCl (VILHC), agomelatine (AGO) or duloxetine HCl (DULHC) and vitamin B12 (cyanocoblamine B12) in bulk, pharmaceutical dosage form and in urine samples. Both similar methods (I and II) were carried out using 0.04 M phosphate buffer (pH 7.0), acetonitrile and methanol in the ratio (30:30:40, v/v) as a mobile phase. Thermo BDS hypersil-C18 column, with 5 µm particle size and 250 × 4.5 mm dimensions, at flow rate 1.0 mL min-1 and UV detection at 277 nm at ambient temperature 25 °C were used. The retention times were 5.12 and 2.54 min for VILHC and vitamin B12, 4.98 and 2.53 min for AGO and vitamin B12, respectively, with linearity range from 0.001 to 200 µg mL-1. However, for the separation of DULHC and B12, UV detection at 230 nm and Agilent Eclipse XDA-C8 (150 × 4.5 mm, 5 µm) column, were used (method III). The retention time of DULHC and vitamin B12 was found to be 4.53 and 1.35 min, respectively, with linearity range from 0.0005 to 200 µg mL-1. The proposed methods were validated as per the ICH guideline with very low LOD and LOQ. The values of %RSD for precision was less than 2% and the value of % recovery were found to be 99.20-100.9% and 99.23-100.67% for determination of the drugs in pure and pharmaceutical formulations, respectively, for all methods confirming that the methods are precise, accurate and selective for separation and determination of VILHC, AGO or DULHC from B12 in tablets and in urine samples without any interference from each other or from common excipients.
