Determination of omeprazole and metabolites in plasma and urine

Omeprazole and three of its metabolites, the sulfone (H 168/66), the sulfide (H 168/22) and the hydroxy metabolite (H 195/80), are determined in plasma and urine by liquid chromatographic methods. The compounds are extracted from the biological sample and the extract is subjected to liquid chromatographic separation, either directly or after evaporation of the organic solvent and dissolution in a polar phase. The effluent from the column is UV-monitored at 302 nm and the quantitative evaluation performed by electronic integrator. Both a method with manual sample work-up and automatic injection and a fully automated system, Technicon FAST-LC, have been employed for the analyses. More than 25 000 samples have been assayed so far by these two methods.