The World Health Organization regards omeprazole among its ‘List of Essential Medicines’ which outlines the most effective and safest medicines required by a country's healthcare system to meet its needs. The United States Pharmacopeia (USP) closely monitors the production of these drugs and provides monographs for identification and impurity testing of the drug substance. This application brief describes the use of the LC 300 liquid chromatography system and SimplicityChrom™ chromatography data system (CDS) for the analysis of omeprazole as per the USP monograph.