A Review of Methodology for Testing Hair for Cocaine

Cocaine is one of the most commonly abused drugs in the world due to its anesthetic and stimulating effects. Although hair testing is not suitable for the detection of a single usage of cocaine such as in roadside testing, its extended window of detection allows drug monitoring over an extended period of time (months to years) in regular cocaine users. As cocaine and its metabolites are not apparent in hair during or immediately after absorption of the drug, this technique is often used as a complimentary test to blood or urine whose detection window is limited to hours or days. A screening test, usually an immunoassay, is initially performed on the hair and any positive results are validated and quantified with a confirmatory test which is generally chromatographic in nature. The sample preparation of hair is one of debate and constant improvement as the matrix is complicated requiring steps such as decontamination from environmental effects, extraction of the metabolites, and derivatization is necessary for use in sensitive analytical equipment. Different screening tests involving immunoassays, confirmatory tests and sample preparation methods are reviewed showing the current scientific advancements in the field focusing on the last ten years as well as any limitations and potential for future development.