Simultaneous Determination of Methocarbamol and Paracetamol in the Presence of Three Related Substances by Ultra Performance Liquid Chromatography

Introduction: A rapid, and accurate Ultra Performance Liquid Chromatography (UPLC) method was developed to simultaneously analyze Methocarbamol, Paracetamol and the related substances. Materials and Methods: Waters ACQUITY UPLC® BEH Phenyl C18 column was used in conjunction with UV detection at 225nm. Gradient elution with 0.05M, pH 6 phosphate buffer and acetonitrile flow at 0.3mL /min rate were used to separate the substances. The retention times for 4-Aminopheno, Paracetamol, Guaifenesin, Methocarbamol, and 4-Chloroacetanilide were 1.319 minute, 2.224 minute, 4.467 minute, 4.769 minute and 5.433 minute respectively. The concentration was linear in the range of 2-100 μg/ml for Methocarbamol, and 1-100 μg/mL for Paracetamol. The percentage recoveries were between 99.28±1.23% to 100.57±0.99% for Methocarbamol, and between 99.08±1.23% to 101.23±1.39% for Paracetamol. Results and Discussion: The validated optimal protocol is robust and accurate for simultaneous analysis of Methocarbamol, Paracetamol and the related substances, applicable for bulk powder as well as pharmaceutical formulation. Conclusion: In this paper, a highly sensitive, accurate, and precise UPLC method with UV-Vis detection was developed and validated for quality control of MET and PAR in bulk as well as in pharmaceutical preparations.