Plasma theophylline level was assayed by EMIT-aad (Syva Corp.), which is a newly developed homogeneous enzyme immunoassay method. The results were compared with those obtained by previously reported high-pressure liquid chromatography (HPLC). esults obtained by the above 2 methods were quite compatible with each other. In a total of 93 specimens from 9 asthmatics, the correlation coefficient was 0.980, the slope 1.047μg/ml, and intercept-0.03μg/ml. CV of replicate analyses on a spiked sample by EMIT was below 7%, and the correlation coefficient of theophylline-spiked sample to EMIT was 0.990. EMIT procedure, in view of its clinical application for determination of plasma theophylline levels, has considerable advantages over hitherto available methods: it requires only 50μl of plasma for a single determination, saves deproteinization and extraction, and is operated in a quite simple method in as short time as 2min.
