Abstract
The development of new, sensitive, and selective methods for pharmaceutical analysis is crucial for ensuring drug safety, efficacy, and quality by enabling precise detection and quantification of active pharmaceutical ingredients, impurities, and degradation products at trace levels. This thesis presents two spectrophotometric methods for the determination of omeprazole in pharmaceutical formulations based on the selective degradation of omeprazole.
The first method exploits the degradation of omeprazole under controlled conditions, followed by coupling of the degraded product with a diazotized compound (4-aminohippuric acid) to form a chromophoric complex. To establish a safe and environmentally friendly approach for the determination of omeprazole, all procedures were conducted at room temperature. Optimizations of degradation conditions and coupling reactions were thoroughly investigated, leading to a robust analytical technique with enhanced sensitivity and specificity. The resulting chromophoric complex exhibits a distinct absorbance peak at 410 nm, enabling accurate quantification of omeprazole concentration in the range of 1.6–56 mg/L and a determination coefficient of 0.9970 with relative standard deviations less than 0.9%, molar absorptivity 1.682×104 L/mol.cm, and Sandell’s sensitivity was 0.0205 μg/cm2. The proposed method was applied for the quantification of omeprazole in real samples with error values less than 3.0%. This method provides a reliable alternative for routine analysis of omeprazole in pharmaceutical formulations.
In the second method, magnesium oxide nanoparticles (MgO NPs) were synthesized via green synthesis using fig leaf extracts as the natural reducing agent. The characterized MgO NPs exhibited an average particle size of 24.3 nm and demonstrated dual functionality for photodegradation and selective spectrophotometric determination of omeprazole. Photocatalytic degradation of omeprazole using MgO NPs under UV irradiation produced an aromatic diamine intermediate, which was subsequently diazotized and coupled with phloroglucinol to form a spectrophotometrically detectable azo dye. The method showed excellent linearity over a 0.025-3.0 mg/L concentration range, with a high determination coefficient (0.9968). The method demonstrated superior sensitivity with a molar absorptivity of 7.62×10⁴ L/mol.cm, and Sandell’s sensitivity of 4.53 μg/cm². The limits of quantification and detection were 0.0772 mg/L and 0.025 mg/L, respectively. Validation studies have confirmed excellent precision and accuracy. The intra- and inter-day precisions showed RSD values of 2.08% and 1.21%, respectively. The recovery studies indicated high accuracy, with recovery percentages ranging from 95.33% to 99.20% across all tested concentrations. The suggested green synthesis approach provides an environmentally sustainable route for MgO NP production, while offering a highly sensitive, accurate, and precise analytical method for omeprazole determination, contributing significantly to green analytical chemistry practices.
