Enzyme multiplied immunoassay technique (EMIT) is a common method for qualitative and quantitative determination of therapeutic and recreational drugs and certain proteins in serum and urine.

[1] It is an immunoassay in which a drug or metabolite in the sample competes with a drug/metabolite labelled with an enzyme, to bind to an antibody.

[5] In the U.S., the cutoff limits must be set in accordance with Mandatory Guidelines for Federal Workplace Drug Testing Programs that were developed by SAMHSA (The Substance Abuse and Mental Health Services Administration is a branch of the U.S. Department of Health and Human Services).

Because of the social and legal consequences, a positive test result must be confirmed by an alternative method, usually Gas Chromatography/Mass spectrometry.

[6] Immunoassays that do not conform with SAMHSA, featuring a cutoff of 20 ng/ml, have been shown to produce false positives from passive inhalation of marijuana smoke.