EMIT
Definition
Enzyme-Multiplied Immunoassay Technique. Homogeneous immunoassay where drug-enzyme conjugate competes with drug in the sample for antibody binding; free conjugate retains enzyme activity, measured spectrophotometrically.
- Full name
- Enzyme-Multiplied Immunoassay Technique
- Type
- Homogeneous competitive immunoassay
- Readout
- Spectrophotometric enzyme activity
Common questions
What does an EMIT result confirm on its own?+
EMIT is a rapid screening test for a drug class in urine or blood. A positive result is presumptive only and needs confirmation by chromatography-mass spectrometry before it can support identifying a specific drug.
Why can EMIT give a false positive?+
Cross-reactivity, where a structurally similar compound, including some over-the-counter medications, binds the antibody and mimics the target drug's signal.
Related terms
- Adulteration
- Deliberate tampering of a urine specimen to defeat the screen. Common adulterants include nitrite, chromate, peroxide, glutaraldehyde, niacin, vinegar and Visine. Detected...
- Confirmatory Test
- A test with sufficient specificity to establish the identity of a biological fluid for reporting purposes. Examples include Takayama and Teichmann crystal...
- Cut-Off Concentration
- The threshold analyte concentration, set by regulatory guidance, above which a specimen is reported as a screen-positive. Choosing the cut-off balances sensitivity...
- Detection Window
- The period after last use during which a drug or its metabolite is detectable in a given matrix. Varies from minutes (blood,...
- MRM
- Multiple Reaction Monitoring. LC-MS-MS or GC-MS-MS mode that follows specific precursor-to-product ion transitions for each target analyte, giving very high selectivity at...
- SAMHSA-5
- The five-drug federal workplace panel of the US Substance Abuse and Mental Health Services Administration: amphetamines, cocaine metabolite, marijuana (THC-COOH), opiates and...
- Screening Test
- A fast, sensitive immunoassay (EMIT, CEDIA, FPIA, KIMS, lateral-flow) that flags a sample as presumptive positive against a class cut-off. Sensitive and...