The sculp hair analysis is a method to prouve a consumption of medicines, illegal drugs such as cannabis, cocaine, ecstasy or heroin and recently also alcohol still after longer time periods (depending upon hair length 2 to 10 months). During the hair formation existing drug and medicine active substances are taken up in the follicle cells from the blood into the hair.
Alcohol reacts with fatty acids to fatty acid ethyl esters (FAEE), which are likewise deposited in the hair. Alcoholic abstinent persons reach approximatly 0.2 ng/mg FAEE, because alcohol is a natural metabolism intermediate. Values above 1.0 ng/mg are typical for excessive consuption.
With unique consumption it comes to a singular deposit, which grows slowly with the growth of the hair outward. The hair length (at least 2 cm) determines therefore the possible prouve duration, whereby the growth rate is approx. 13 mm/month, at least 10 mm/month. In cases of missing or too short sculp hair also axillary hair or hair of the intimate area is used.
Rinsing out of the materials by frequent hair washing is not possible. For analysis, the washed hair is divided as finely as possible and afterwards the substances, together with an internal standard are extracted by acids or bases. After extraction the analysis takes place by means of gas chromatography/mass spectrometry (GC/MS) with detection limits from approximatly 0.1 to 1 ng substance per mg hair.
The determination of cannabinoids (THC) is made by dissolving the hair in a solution of sodium hydroxide, followed by liquid extraction, derivatization and measurement with SPE-GC/MS.
The analytical rules, the process of determination in the laboratory and the detection limits are defined by the internationaly by the Society of Hair Testing. For each drug the following limits of quantification (LOQ) and boundary conditions are defined:
- Opiates: 0,2 ng/mg, for heroin detection 6-Acetylmorphine has to be proved
- Cocaine: ≤ 0,5 ng/mg, metabolites ≤ 0,05 ng/mg
- Amphetamines: ≤ 0,2 ng/mg for every single drug
- Cannabinoides: THC ≤ 0,1 ng/mg, THC-COOH ≤ 0,2 pg/mg
