Glycerol as a new mobile phase modifier for green liquid chromatographic determination of ascorbic acid and glutathione in pharmaceutical tablets

Abstract

Fixed dose combinations of glutathione and ascorbic acid are marketed due to the synergetic effect of glutathione, which regenerates ascorbic acid, potentiates its action and prolongs its antioxidant potential. In this work, glycerol was introduced for the first time as a green mobile phase modifier for liquid chromatographic determination of glutathione and ascorbic acid in pharmaceutical tablets. The viscosity barrier was overcome by using water as a co-fluidifying solvents and by controlling the column temperature. Compared with methanol and acetonitrile, glycerol could result in better peak shapes and superior system suitability. To explore the retention process, free energy and enthalpy-entropy compensation were calculated for both glutathione and ascorbic acid. The chromatographic conditions were optimized using factorial design with the aid of Minitab 17® Software. The method was successfully validated according to the guidelines of the International Conference on Harmonization Q2 (R1) and was found linear in the range of 1 μg/mL to 300300 μg/mL for both drugs. The method was evaluated in terms of its greenness and then compared to the reported method. Glycerol has several advantages over commonly employed mobile phase modifiers, such as the high safety, the low UV cut-off point, low flammability, low volatility, the green features, and the biodegradability. This work paves the way for more applications of glycerol in green liquid chromatography.