Variation in results of cost-effective EMIT assays on the Cobas-Bio analyser.

Following suggestions that spurious results occur with EMIT assays--so-called 'fliers'--many laboratories perform such assays in duplicate. In this study, using a Cobas-Bio centrifugal analyser and cost-effective assays developed in the authors' laboratory, complete EMIT assays were run, each with its own calibration curve, on three anti-epileptic drugs using plasma samples, and five drugs of abuse using urine samples. No serious spurious results were obtained. It is suggested that there is no inherent tendency for EMIT assays to produce 'fliers' and that when these occur they may be explained by factors common to many other types of assay.