Thin-layer chromatography‒densitometric method for the simultaneous determination of paracetamol and methocarbamol in their dosage form

An accurate, sensitive, and precise thin-layer chromatography‒densitometric method was developed for the simultaneous determination of methocarbamol and paracetamol. The separation was conducted on silica gel 60 F₂₅₄ plates using ethyl acetate‒n-heptane‒glacial acetic acid‒ammonia (30:10:4:0.5, V/V) as the mobile phase. Detection was performed at 273 nm. Methocarbamol and paracetamol were well resolved with retardation factor values of approximately 0.55 ± 0.02 and 0.78 ± 0.02, respectively. The method was validated according to the International Council for Harmonisation (ICH) Q2R1 guidelines and exhibited a linearity range of 0.2‒4.0 µg/band for paracetamol and 0.1‒1.0 µg/band for methocarbamol. It was successfully applied to the analysis of both drugs in standard solutions and pharmaceutical formulations with a mean percentage recovery of 98‒102%. The method was statistically compared with a spectrophotometric reported method; no significant difference was determined. The greenness and blueness of the developed method were also assessed, revealing the eco-friendliness and practicality of the developed method. The method could be used in quality-control labs for the simultaneous analysis of both drugs in raw materials, diluted solutions, and pharmaceutical preparations.