Analysis of etodolac and diclofenac in pure and pharmaceutical forms using ionic-liquid dispersive liquid–liquid microextraction and RP-HPLC technique

In this research, etodolac and diclofenac were determined using ionic-liquid dispersive liquid–liquid microextraction (IL-DLLME), followed by dilution/back-extraction with ethanol, and then analyzed by reversed-phase high-performance liquid chromatography (RP-HPLC). Each drug was measured at 274nm and 279nm for Diclofenac (DIC) and Etodolac (ETO), respectively. Beer's law was obeyed in the linear ranges of 0.6-20 µg mL-1 for Diclofenac sodium (r = 0.999) and 0.5-35 µg mL-1 for etodolac (r = 0.997). The relative standard deviation (RSD%) and detection limit were 1.623% and 0.102 µg mL-1 for Diclofenac, and 1.607% and 0.098 µg mL-1 for Etodolac. The chromatographic system consists of an HPLC equipped with a C18 column (250 mm x 4.6 mm). The mobile phase consisted of methanol/acetonitrile: phosphate buffer (pH=5-6) in the ratio of 55:45 v/v at a flow rate of 1.0 mL min-1. This method has been successfully applied to determine diclofenac and etodolac, which is a cost-effective and straightforward method that allows the simultaneous analysis in tablet dosage forms in pharmaceutical formulations, where the error and recovery ratios for diclofenac (100 mg) were obtained at 4.17%, 95.83%, and etodolac (400 mg), 3.25%, 96.75%, respectively. RP-HPLC methods based on ionic liquid extraction exhibit high sensitivity, linearity, and repeatability for the detection of etodolac and diclofenac in their pure and pharmaceutical forms.