Fast filtration enzyme immunoassay for haptens.

An immunometric method for determination of hapten concentration in fluids has been developed. High-affinity hapten-specific enzyme-labeled monoclonal antibodies are mixed with a sample containing hapten, then the mixture is filtered through a membrane with immobilized hapten. The level of enzyme activity retained by the membrane is inversely proportional to the concentration of hapten in a sample. The assay has been developed for theophylline, digoxin and phenobarbital. The coefficient of variation is less than 5% and the test takes about 2 min.