Production of antibodies and development of enzyme immunoassay for determination of monensin in biological samples.

Monensin is converted to monensin bromoacetate, which provides successful coupling to protein and allows production of monensin-specific rabbit antisera. A modified indirect enzyme-linked immunosorbent assay (ELISA) was developed, which is highly sensitive (2 ng/mL) to monensin determination. Monensin recovery was 53-81% at 10 ppb in sera or urine, and 81-130% at 100 ppb in dichloromethane-extracted feces or water. Overall recovery was 98.8% with coefficients of variation from 6 to 52% over the range of monensin concentrations studied. This is the first immunoassay reported for the carboxylic ionophore antibiotics.