A totally automated system for enzyme immunoassay of theophylline in serum

We describe a procedure for enzyme immunoassay of theophylline (1,3-dimethylxanthine) in which all phases of the assay are totally automated in a Kinetic Analyzer (KA-150). This system permits assay of 75 10-mul samples per hour, with results available at 30-s intervals after initial sample preparation and preincubation. We compared results for 138 clinical samples by an ultraviolet method (x) and the present method (y). The slope of the comparison curve was 0.902, the y-intercept 0.402, and the correlation coefficient 0.984. The coefficient of variation for samples run in duplicate on the same day was 4.9%; it was 8.1% for samples run on different days. Specificity, sensitivity, simplicity, speed, and small reagent requirement all make this an attractive alternative to chromatographic procedures.