Table 1.

Criteria for classifying cross-reactivity of compounds.

Classification	Definition
DOA/Tox assays
Target compound	For a given DOA/Tox assay, the drug or drug metabolite used as the antigenic (hapten) target (e.g., morphine for opiates assay)
Strong true positives	Within-class compounds causing cross-reactivity equal to the positive cutoff of the assay at concentrations of less than 10,000 ng/mL
Weak true positives	Within-class compounds causing cross-reactivity equal to the positive cutoff of the assay at concentrations of 10,000 to 100,000 ng/mL
Strong false positives	Out-of-class compounds causing cross-reactivity equal to the positive cutoff of the assay at concentrations of less than 10,000 ng/mL
Weak false positives	Out-of-class compounds causing cross-reactivity equal to the positive cutoff of the assay at concentrations of 10,000 to 100,000 ng/mL
True negatives	Out-of-class compounds causing no cross-reactivity or cross-reactivity equal to the positive cutoff of the assay only at concentrations of greater than 100,000 ng/mL
False negatives	Within-class compounds causing no cross-reactivity or cross-reactivity equal to the positive cutoff of the assay only at concentrations of greater than 100,000 ng/mL