Measurement of diphenylhydantoin and phenobarbital by enzyme immunoassay and gas-liquid chromatography.

A new enzyme-multiplied immunoassay technique (EMIT) was compared with Kupferberg's gas-liquid chromatography (GLC) for the determination of diphenylhydantoin and phenobarbital. 116 plasma samples of patients with epilepsy were examined simultaneously by EMIT and GLC. The precision of repeated determinations was similar for both procedures. There was good agreement between the EMIT and GLC results. The rapid and precise analysis, made possible by the EMIT system, is useful for the treatment of epilepsies.