Use of High Performance Liquid Chromatography for the Determination of Cocaine and Benzoylecgonine in Human Hair

Abstract

A high performance liquid chromatographic method involving diode array detection (HPLC–DAD) is proposed for the determination of cocaine and benzoylecgonine in human hair. Samples were washed, dried, and subjected to enzyme hydrolysis and liquid–liquid extraction in Toxitubes A® prior to analysis on a Nova‐Pak C18 (150 × 3.9 mm) column with a 70:30 (v/v) methanol–0.02 M phosphate buffer pH 7, at a constant flow‐rate of 0.4 mL/min as the mobile phase, and articaine as reference compound. The detector response was linear over the concentration range 2–200 ng/mg hair for both drugs. The detection and quantitation limits were 1 ng/mg and 2 ng/mg, respectively. The precision was quite acceptable, with coefficients of variation less than 5%. An overall 52 specimens from cocaine users were analysed with the proposed method and found to contain cocaine and benzoylecgonine concentrations over the ranges 4.2–554.7 ng/mg (average 57.3 ng/mg) and 0–1167.6 ng/mg (average 159.7 ng/mg), respectively.

Keywords:

• HPLC–DAD
• Cocaine
• Benzoylecgonine
• Hair