Evaluation of a new ELISA kit for the detection of benzodiazepines in meconium.

Two versions of enzyme-linked immunosorbent assay (ELISA) kits designed for the detection of benzodiazepine drugs and metabolites (Immunalysis) were evaluated for use with meconium specimens. One was an older kit, and one was a new replacement kit developed for better detection of several commonly prescribed benzodiazepines and metabolites. The kits were evaluated by analyzing 68 patient specimens previously analyzed by liquid chromatography-tandem mass spectrometry and eight quality control samples. In addition to the recommended calibrator (oxazepam), clonazepam was evaluated as an alternate calibrator for the new kit. Detection and sensitivity for some analytes was improved using the new ELISA kit, but was reduced for others. The new kit using clonazepam as the calibrator provided the most sensitive assay for detection of the 11 benzodiazepines and metabolites reported here.