Figure 2

Variability in sensitivity of marketed amphetamine and benzodiazepine screening immunoassays. The plotted circles indicate the concentration of compound that produces an equivalent reaction to 1000 ng/mL d-amphetamine (amphetamine assays) or 200 ng/mL diazepam (benzodiazepine assays). The dashed lines bracket clinically or toxicologically relevant concentrations from studies in the published literature (see text of Results for detailed description). A) Amphetamine assays. With one exception (Roche cobas c assay), marketed amphetamine screening immunoassays detect amphetamine and methamphetamine well but have variable and often low cross-reactivity with MDA, MDMA, MDEA, and phentermine. B) Benzodiazepine assays. Marketed benzodiazepine screening immunoassays generally have higher sensitivity to diazepam, oxazepam, and nordiazepam than to 7-aminoclonazepam (main clonazepam urinary metabolite) or lorazepam glucuronide (main lorazepam urinary metabolite).