Optimization and Validation of a Stability-Indicating RP-HPLC Method for Dual Drug Analysis of Aspirin and Omeprazole

A reverse-phase high-performance liquid chromatographic (RP-HPLC) technique capable of indicating stability was established and validated for the concurrent measurement of Acetylsalicylic acid and Omeprazole in combined pharmaceutical products. Separation was carried out on a Luna Phenyl Hexyl column (250 × 4.6 mm, 5 µm) with a mobile phase composed of Acetonitrile and 0.1% Perchloric acid mixed at 20:80 (v/v), delivered at 1.0 mL/min. The detection wavelength was set at 249 nm, representing the isosbestic point for both substances, with an overall analysis duration of 5 minutes. The retention times recorded were 2.038 min for Acetylsalicylic acid and 2.995 min for Omeprazole, showing a resolution factor of 4.63. The procedure was validated following ICH criteria for selectivity, response linearity, recovery, repeatability, intermediate precision, durability, detection limit, and quantitation limit. The calibration plots exhibited outstanding linearity, with recovery percentages and %RSD values falling within prescribed limits. Stress degradation experiments involving acidic, basic, oxidative, reductive, thermal, photolytic, and hydrolytic conditions verified the method's ability to separate intact drugs from breakdown products, as purity angles remained below purity thresholds. The method showed strong sensitivity, with LOD/LOQ values calculated as 0.49/1.62 µg/mL for Acetylsalicylic acid and 0.24/0.80 µg/mL for Omeprazole. This validated procedure is straightforward, reproducible, accurate, and appropriate for routine quality monitoring.