Detection Window
Definition
The period after last use during which a drug or its metabolite is detectable in a given matrix. Varies from minutes (blood, oral fluid) to months (hair).
- Field
- Drugs of abuse testing
- Range
- Minutes to months depending on matrix
- Shortest matrix
- Blood, oral fluid
- Longest matrix
- Hair
Common questions
Why does matrix choice matter when interpreting a positive result?+
A positive in blood or oral fluid points to recent use, often within hours to a day or two, while a positive in hair can reflect use from weeks or months earlier, so the same drug finding supports very different conclusions about timing depending on which matrix produced it.
Does a negative result outside the detection window rule out use?+
No. A negative only means the drug or metabolite was not present above the detection threshold at the time of sampling and within that matrix's window, so a person who used the drug earlier than the window covers can still test negative despite genuine prior use.
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...
- EMIT
- Enzyme-Multiplied Immunoassay Technique. Homogeneous immunoassay where drug-enzyme conjugate competes with drug in the sample for antibody binding; free conjugate retains enzyme activity,...
- 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...