Analysis of omeprazole and its main metabolites by liquid chromatography using hybrid micellar mobile phases

In this work, direct injection and UV detection set at 305 nm was used. Omeprazole and its metabolites were eluted in less than 11 min with no interference by the protein band or endogenous compounds. Adequate resolution was obtained with a chemometric approach, in which the retention factor and shape of the chromatographic peaks were taken into account. The analytical parameters including linearity (r > 0.9998), intra- and inter-day precision (RSD, %: 0.6-7.9 and 0.14-4.7, respectively) and robustness were studied in the validation of the method for the three compounds. The limits of detection and quantification were less than 6 and 25 ng mL−1, respectively. Recoveries in micellar medium, plasma and urine matrices were in the 98-102% range. Finally, the method was successfully applied to the determination of omeprazole and its metabolites in physiological samples. Omeprazole was also analysed in pharmaceutical formulations.