Validated stability indicating reverse phase liquid chromatography method for oxcarbazepine and its degradation...

Oxcarbazepine is a widely prescribed anticonvulsant used in the management of epilepsy through modulation of abnormal neuronal excitability. The objective of the present study was to synthesize oxcarbazepine in the laboratory and develop a reliable, stability-indicating, and environmentally conscious reverse-phase high-performance liquid chromatography (RP-HPLC) method for its quality assessment, including the quantification of impurities and degradation products. Oxcarbazepine was synthesized and characterized using infrared spectroscopy (IR), nuclear magnetic resonance (NMR), and high-performance liquid chromatography (HPLC) techniques. Chromatographic separation was achieved using a Supelco Discovery C18 column (4.6 × 250 mm, 5 µm) with a mobile phase consisting of 75% potassium phosphate monobasic buffer (pH 5.0) and 25% acetonitrile at a flow rate of 1.0 mL/min. Detection was performed at 257 nm, and oxcarbazepine exhibited a retention time of approximately 11 min. The developed RP-HPLC method was validated according to ICH, USP, and FDA guidelines. Forced degradation studies were conducted under acidic, basic, oxidative, thermal, and photolytic conditions to evaluate the stability-indicating capability of the method. In addition, the environmental impact of the analytical procedure was assessed using Green Analytical Chemistry (GAC) metrics, including the Analytical Eco-Scale, GAPI, and AGREE tools. The developed method demonstrated excellent specificity, linearity, accuracy, precision, robustness, and sensitivity. All degradation products were well resolved from the parent oxcarbazepine peak, confirming the stability-indicating nature of the method. Excellent linearity was observed over the concentration range of 0.24-2000 ppm with a correlation coefficient (R2) of 0.9995. Accuracy values ranged from 99.4% to 101.5%, while the limit of detection (LOD) and limit of quantification (LOQ) were 0.3 ppm and 0.9 ppm, respectively, indicating high sensitivity suitable for trace-level analysis. Robustness studies confirmed the reliability of the method under deliberate variations in chromatographic conditions. Furthermore, greenness assessment revealed an Analytical Eco-Scale score of approximately 75, a GAPI pictogram with predominantly green and yellow zones, and an AGREE score of 0.57/1.0, indicating moderate environmental friendliness. Overall, the validated RP-HPLC method provides a reliable, precise, sensitive, stability-indicating, and environmentally conscious analytical approach for routine quality control, impurity profiling, and stability studies of oxcarbazepine in raw materials and pharmaceutical formulations.