• Hair Drug Testing Methods

    Minute methodological insides:

    Amongst several methodologies that have been developed in the last few decades to trace the drug abuse, Hair-drug testing method is gaining wide acceptance & popularity due to its high accuracy & efficiency, not to mention the ease of performing the test itself! This test uses the hair segments as samples to detect the traces of certain drugs & analyze them quantitatively to determine if they amount over the permitted metabolite cut-offs.

    This technique is principally quite simple. As and when a person ingests steroids, upon first pass metabolism by liver, these steroids are converted to various metabolic products or metabolites, as they are known commonly. These metabolites then "go rafting" in the blood stream "for a ride" in the body! In case these steroids are injected in, instead of taken orally, they escape first pass metabolism by the liver and pass as such in the blood stream. Now as these metabolites enjoy their ride, they approach the hair shaft. The blood arteries here are connected to the hair shaft and deliver the metabolites to the hair follicles. In due course of time, through these follicles, the metabolites are entrapped into the core of the shaft i.e. the cortex of the hair fiber.

    As the hair grows, new metabolites are added at the bottom, with the old metabolites at the top. Hence a one and half or two inch long hair segment with follicle attached can be used to draw a complete map of the drug history of an individual.

    The metabolites "rest-in-peace" inside the hair fibers as they cannot be bleached, washed or flushed away as the shampoos and other cleansing agents act only on the upper surface of the hair.


    There are several hair drug testing kits available in the market. One can use these kits directly for the chemical analysis or else can elaborate his own methodology for this purpose. No matter which method is used, one should take care while preparing the sample for the test.

    Preparation of sample:

    It refers to cleansing or washing out impurities & contaminants from the outer surface of the hair. This can be done using various chemicals which should be selected so that ingested metabolites do not wash out. One can use shampoos or organic solvents like methylene chloride, surfactants, acetone etc.

    There are three domains in the hair fiber, 

    • The surface domain: The surface of the hair where most external contamination occurs. This can be cleaned by washing with non-swelling solvents like ethanol. 
    • The accessible domain: The middle point of hair shaft that may have slight contamination. For cleansing, swelling agents like water can be used, that open up the outer matrix for the contaminants to come out. 
    • The inaccessible domain: It is by far the largest domain and cannot be contaminated even by soaking a hair in the drug solution. Hence it contains only the drug metabolites from the blood.


    One should not use the chemicals which may result in dilution of metabolites as it may lead to reduced test sensitivity & thus missing out metabolites which are present in minute amounts.

    Drug Screening: 

    The drug metabolites are screened from the cortex of the hair. The metabolites are extracted out from the sample, purified and finally, concentrated. The concentrated metabolites are then analyzed qualitatively & quantitatively by using various chromatography techniques and thus, complete drug profiles can be created from just few mighty hairs!

    Categories: Drug Testing for a Drug-Free Home

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