Decontamination
Definition
The wash protocol applied to hair or nails before extraction, intended to remove sweat, sebum and external contamination so that the assay reads only what was incorporated from blood at the time of growth.
- Applies to
- Hair and nail specimens before extraction
- Removes
- Sweat, sebum, and external surface contamination
- Purpose
- Ensures the assay reflects internal, not surface, drug loading
- Field
- Toxicology, biological matrix preparation
- Contrast
- Distinct from the more elaborate multi-solvent decontamination wash
Common questions
Why is decontamination essential before hair or nail drug testing?+
Hair and nails can pick up drug residue from the environment, such as smoke exposure or handling contaminated surfaces, without any of it being metabolised and incorporated into the keratin. Without decontamination, that surface residue could be mistaken for evidence of actual drug use or exposure.
Can decontamination alone rule out passive external exposure as an explanation for a positive result?+
Basic decontamination reduces but does not fully eliminate that risk, which is why more rigorous protocols retain and separately analyse the wash solvent, so the analyst can compare internal versus external drug loading and address a passive-exposure argument directly.
Related terms
- Femoral Blood
- Peripheral venous blood drawn from the femoral vein after clamping it off proximally. Considered the gold-standard antemortem-equivalent matrix because it is anatomically...
- Matrix
- The biological tissue or fluid (or non-biological substance) in which the analyte is suspended. The matrix decides extraction chemistry, recovery and the...
- Post-Mortem Redistribution (PMR)
- The phenomenon where drug and poison concentrations shift between body compartments after death, generally moving out of solid organs back into the...
- Viscera
- The standard set of organs and fluids collected at a suspected poisoning autopsy in India: stomach with contents, a length of upper...
- Vitreous Humour
- The gel-filled interior of the eye, anatomically isolated from hepatic and gastric post-mortem redistribution sources. In forensic toxicology of hooch deaths, vitreous...