Melanin Binding
Definition
The non-covalent association of basic and lipophilic drugs (cocaine, opiates, amphetamines, nicotine) with melanin granules in the hair cortex. Pigmented (black, brown) hair retains substantially more drug than blonde or grey hair from the same dose, producing the well-known hair-colour bias in concentration readings.
Related terms
- Anagen Phase
- The actively growing phase of the hair follicle, during which the keratinocyte is in contact with the dermal papilla capillary and incorporates...
- 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...
- Decontamination Wash
- A multi-solvent surface wash (typically dichloromethane, methanol and aqueous buffer) applied before digestion to strip externally deposited drug from the cuticle. The...
- Parent-to-Metabolite Ratio
- The ratio of an intact drug to its in vivo metabolite in hair, used to distinguish genuine ingestion (which produces both) from...
- Segmental Analysis
- The practice of cutting collected hair into sequential 1 cm lengths from the root end and analysing each segment separately. Each centimetre...
Explained in
- Hair Analysis for Drugs and Chronic PoisoningThe non-covalent association of basic and lipophilic drugs (cocaine, opiates, amphetamines, nicotine) with melanin granules in the hair cortex. Pigmented (blac...