Abstract
Since 1971 enzyme immunoassay techniques have been used to estimate hormones and drugs in biological fluids. This thesis describes the development of enzyme immunoassays (EIAs) for measuring serum concentrations of nortriptyline, methotrexate, and triiodothyronine. The resultant assays appear to compare favourably with presently used methods for estimating these compounds. The basis of enzyme immunoassay for bile acids has also been established. The principle of using simultaneous EIA for multicomponent mixtures has also been demonstrated using solutions containing triiodothyronine and thyroxine. In this simultaneous assay B-D-galactosidase was conjugated to T[3] and alkaline phosphatase was conjugated to T[4]. The bifunctional imidoester dimethyl adipimidate appeared to be the most satisfactory linking agent for each enzyme. In the other assays B-galactosidase alone was used as the enzyme label. In order to separate free and bound labelled material prior to measurement of enzyme activity a second antibody (post or pre precipitation) techniques were found to be very satisfactory. The techniques which are described should be applicable with minor modifications to the assay of a wide range of endogenous and exogenous compounds in biological fluids.