Glycerol-Based Green RP-HPLC Method for Simultaneous Determination of Methionine and Paracetamol in Pharmaceutical Tablets

Methionine and paracetamol are combined in dosage forms due to the ability of methionine to compensate the deficiency in glutathione in hepatic patients. In this work, an innovative simple time-saving green RP-HPLC method using glycerol as a solely green mobile phase with water for the first time was developed for the simultaneous determination of methionine and paracetamol in their standard and in Hepamol® tablets. The chromatographic conditions were optimized using factorial design with the aid of Minitab 17® Software. The method was performed on a C18 column at 38 °C, and a mobile phase consisting of glycerol and phosphate buffer (pH 2.4) (40:60, v/v), using diode array detector at 210 nm. The mixture was separated in 5 min. The developed method was validated in accordance with ICH requirement over linearity ranges of 10–90 μg/mL for both drugs, and LODs were 3.33 μg/mL for both methionine and paracetamol. Glycerol has high safety, low UV cut-off point, low flammability, and its viscosity can be manipulated when diluted with water. The procedure was compared to the reported reversed phase liquid chromatography method in the terms of their greenness with the green analytical procedure index and the analytical eco-scale. This work breaks new ground for scientists to use glycerol in greener RP-HPLC applications.