Enzyme immunoassay for captopril

A simple enzyme immunoassay for the determination of captopril was developed. A specific antibody for captopril was produced in rabbits that were immunized with a hapten-bovine immunoglobulin G conjugate, which was prepared by using 4-(maleimidomethyl)cyclohexane carboxylic acid as a spacer group. The limit of detection in plasma is 0.5 ng/mL. The assay has an adequate specificity, so isolation of captopril is unnecessary.