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A Novel Method for the Detection of Cocaine in Hair using a Freeze/Thaw Method and GC/MS Analysis

NCJ Number
Romanian Journal of Legal Medicine Volume: 20 Issue: 4 Dated: 2012 Pages: 291-296
Date Published
6 pages

In this article, the authors describe the process and outcomes of their examination of the freeze/thaw method via gas chromatography/mass spectrometry as a possibility for decreasing sample preparation for the detection of cocaine in hair samples.


In order to create an efficient and less strenuous method for the detection of cocaine in hair, a simple freeze/thaw extraction method was developed and coupled to gas chromatography/mass spectrometry (GC/MS). GC/MS analysis parameters were determined by testing solutions of cocaine and two of its metabolites, cocaethylene and ecgonine methyl ester. Ions from these compounds and two pyrolysis products, anhydroecgonine methyl ester and 3-ethoxy-4-methoxyphenethylamine, were chosen in order to test samples using selected ion monitoring (SIM). The qualitative limit of detection for anhydroecgonine methyl ester, 3-ethoxy-4-methoxyphenethylamine, ecgonine methyl ester, cocaine, and cocaethylene were 0.1, 0.1, 0.50, 0.05, and 0.05 ng, respectively. Using cocaine-positive hair samples from Willow Laboratories in Lynn, Massachusetts, U.S., the authors developed an extraction method where tested hairs were washed, segmented, covered in acetonitrile, frozen and thawed for five cycles, and evaporated until a minimal amount of liquid remained. Results were obtained with 2ul of extract using GC/MS with SIM. Ions specific for cocaine were identified in the cocaine-positive hair samples, allowing for cocaine-positive hair samples to be distinguished from cocaine-negative hairs. Utilizing this method, results can be obtained with as little as 10mg of hair, though 20mg is recommended. A blind testing study with samples from Willow Laboratories provided results that were consistent with those obtained by other methodologies employed by Willow Laboratories. Thus, the authors conclude that the freeze/thaw method via GC/MS analysis is a viable method that significantly decreases sample preparation by improving upon the ease of extraction for the detection of cocaine in hair. Publisher Abstract Provided

Date Published: January 1, 2012