ABSTRACT
A number of radioimmunoassays were developed and successfully used for many years for the measurement of drugs in forensic and clinical laboratories. The cost of therapeutic drug monitoring and drug of abuse testing assays on automated immunoassay analyzers are more expensive than assays for the respective analytes on automated clinical chemistry analyzers. There are at least 20 automated immunoassay analyzer systems commercially available in the US for toxicology assays produced by at least 12 different manufacturers. The drug in the sample and the reagent drug-enzyme conjugate are cycled from a sample well in and out of the solid-phase receptacle. All of the automated analytical systems use nonisotopic techniques, such as immunoneph-elometry, fluorescence polarization, fluorescence immunoassay, enzyme immunoassay, or chemilu minescence. Homogeneous assays are more susceptible to endogenous interferences, such as hemoglobin, bilirubin, or lipids. The measurement of fluorescence production in an assay can produce a very sensitive analysis.
