A chromatography method for the screening and confirmatory detection of dexamethasone

Corticosteroids, such as dexamethasone, have been illegally used as growth promoting agents to obtain an economical benefit from increased muscle development. These substances remain in meat and other animal products and may have negative toxic consequences for consumers. A screening and confirmatory method for dexamethasone detection in feed and drinking water in livestock has been developed and validated. This method is based on immunoaffinity chromatography followed by reverse-phase high-performance liquid chromatrography (IAC-HPLC) with diode array detection (DAD) at 242nm. Flumethasone was used as internal standard. The method has been validated according to the European Union regulation 2002/657/EC for banned substances and, thus, the specificity, decision limit, detection capability, recovery and repeatability have been determined. The decision limits (CCα) were 26ng/mL for water and 190ng/g for feed while detection capabilities (CCβ) were 30ng/mL for water and 217ng/g for feed. The method showed good accuracy and precision. The stability of dexamethasone under frozen storage has been studied over a 3.5-month period. No losses were observed, thus confirming that water samples taken by inspectors can be stored frozen for a few weeks until analysis. This method has proved to be relatively simple and useful for rapid screening and confirmation of the presence of dexamethasone in water and feed used for meat-producing animals.