Development and validation of green spectrophotometric methods for simultaneous determination of etoricoxib and tramadol.

To develop and validate simple, precise, and eco-friendly UV spectrophotometric methods for the simultaneous estimation of etoricoxib (ETO) and tramadol hydrochloride (TRA) in combined dosage form. Two UV spectrophotometric methods, simultaneous equation and first-derivative zero-crossing, were established using methanol as solvent. Absorbances were measured at 279 nm and 217 nm for the simultaneous equation method, while zero-crossing wavelengths at 302 nm (ETO) and 283 nm (TRA) were used for the derivative method. Validation followed ICH Q2(R1) guidelines. Linearity was observed in the range of 2-23 µg/mL for ETO and 3-40 µg/mL for TRA with coefficient of determination (r²) = 0.9998. Detection limits for the simultaneous equation method were 0.362 µg/mL for ETO and 0.674 µg/mL for TRA, while the first derivative method provided slightly improved sensitivity with LOD of 0.326 µg/mL for ETO and 0.602 µg/mL for TRA. Accuracy studies yielded recoveries close to 100% for both analytes, and precision results indicated relative standard deviations of less than 2%. The proposed UV methods are accurate, precise, and environmentally benign, offering cost-effective and green alternatives to chromatographic analysis for routine quality control of ETO and TRA formulations.