RAPID FLUORESCENCE ENZYME-LINKED-IMMUNOSORBENT-ASSAY FOR DEXAMETHASONE IN EQUINE URINE

A simple and sensitive competitive ELISA with a fluorescent end-point has been developed for the measurement of dexamethasone in equine urin e samples. Use of pre-mixed reagent of untreated sheep antiserum and a lkaline phosphatase-labelled second antibody enables the analysis of 4 0 duplicate urine samples within 55 min. The assay has good precision (RSD less than 10% for within and between assay runs) and is reasonabl y sensitive (LOD equivalent to 174 ng ml(-1) of diluted equine sample) . The assay has been used to detect the drug over 23 h in urine from a race horse following intramuscular injection of 20 mg of dexamethason e sodium phosphate.