Glossary

Screening cutoff

The concentration above which the immunoassay screen flags a sample as non-negative.

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Screening cutoffs are set higher than confirmation cutoffs because immunoassay is less precise. For example, the federal THC-COOH screening cutoff is 50 ng/mL and the confirmation cutoff is 15 ng/mL.

Related terms & pages

Glossary

Cutoff level

The concentration threshold at or above which a sample is reported as non-negative.

 Glossary

Immunoassay

The initial screening method that uses antibodies to detect drug classes — fast but less specific than confirmation.