Enzyme immunoassay method for comprehensive drug screening in micro-samples of urine

We adapted the reagents from 11 different enzyme-multiplied immunoassay technique (EMIT; Syva Co., Palo Alto, CA 94304) drug-detection kits for use in a centrifugal analyzer. The antibody reagents were mixed into a single dilute solution, and the enzyme-labeled drug derivatives were combined similarly (Mixed EMIT reagents), for use in testing urine samples for the presence of multiple drugs. The assay, a rapid comprehensive drug-screening technique, requires 100 microL of sample and is capable of testing seven samples, in duplicate, simultaneously, in less than 10 min. Clinical evaluation (n = 325) by comparison with thin-layer chromatography (TLC) had the following results: 230 samples were negative by TLC and Mixed EMIT, 77 samples were positive by TLC and Mixed EMIT, 16 samples were negative by TLC and positive by Mixed EMIT, and two samples were positive by TLC and negative by Mixed EMIT.