Objective: The objective of the study was to develop and validate a novel, specific, precise, and simple reversed-phase high-performance liquid chromatography method for the estimation of guaifenesin present in methocarbamol API and its pharmaceutical dosage forms. Methods: The baseline separation for methocarbamol and guaifenesin was achieved by utilizing a Inertsil ODS C18 (250 mm × 4.6 mm) 5 μm column particle size and an isocratic elution method. The mobile phase contains a mixture of water and acetonitrile in the ratio of 70:30 v/v, respectively. The flow rate of the mobile phase was 1.0 mL/min with a column temperature of 25°C and detection wavelength at 272 nm. The method was validated for a limit of detection (LOD), limit of quantification (LOQ), linearity, accuracy, and reproducibility with the help of the exhibit and simulated samples. Results: The LOD for guaifenesin was 0.62 μg/mL. The LOQ for guaifenesin was 1.87 μg/mL. The correlation coefficient obtained for impurity was >0.99. The recovery was obtained for impurity was 106.56% at 50%, 95.20% at 100%, and 100.45% at 150%. In tablet analysis, we can found 0.26% (<0.5%). Conclusion: The developed method was validated as per the ICH guidelines with respect to specificity, precision, linearity, accuracy, LOD and quantification, ruggedness, robustness, and solution stability.
