Urinary amphetamines, benzodiazepines and methadone: cost-effective detection procedures.

Cost-effective immunoassays for the detection of amphetamines, benzodiazepines, and methadone in urine have been developed using Syva EMIT reagents and a Cobas Bio centrifugal analyser. With this method up to 2470 samples can be assayed with a single 100 test EMIT kit while maintaining acceptable precision. Mean CVs of 3.8-6.6% were obtained for concentrations around the manufacturer's recommended threshold level (300 micrograms/l). Comparison of the methods with the Abbott TDx system showed good correlation for methadone. The methods compared less well for amphetamines, and it was not possible to obtain a useful correlation for benzodiazepines. Heat treatment prior to analysis did not affect the detection of benzodiazepines and methadone; there was a mean decrease of 14% for amphetamines.