Immunoassay for glucuronide metabolites of LSD

To improve the screening of subjects for LSD exposure, an immunoassay system is provided for detection of glucuronide metabolites. The detecting antibody binds a competitive binding compound (typically a labeled form of LSD), in a manner that is inhibitable by glucuronide metabolites of LSD and optionally also the parent LSD compound. The system typically has remarkably little cross-reactivity with potential interfering substances such as chlorpromazine and ergotamine, and a low false-positive rate in a panel of clinical test samples. By testing for glucuronide metabolites, the diagnostic window for detecting potential LSD exposure is extended for several days.