Determination of cocaine and its metabolites in blood by gas chromatography coupled with mass spectrometry (GC-MS)

Abstract

Introduction. This article aims to present a simple and sensitive chromatographic method, carried out in the gas phase using detection by mass spectrometry to identify and quantify cocaine and its metabolites in the blood, notably Benzoylecgonine and Ecgonine Methyl ester. Methods. This method involves liquid-liquid extraction using a mixture of solvents, consisting of chloroform and isopropanol, followed by silylation. The separation was carried out using an xi-5ms column (Restek®) of 30 m in length, 0.25 mm in internal diameter and 25 μm in film thickness. Results. Blood level quantification of Benzoylecgonine and Methylester Ecgonine was possible with respective quantification limits of 18 and 39 ng/mL. The method is linear over a range of 75 to 1000 ng/mL and the extraction yields range between 81% and 97%. Regarding the intra- and inter-run precision and the accuracy of the method, the coefficients of variation and biases at the three concentration levels (150, 300 and 750 ng/mL) are well below 15%. This method can easily be applied to blood samples, both in emergency toxicology and in forensic toxicology, to confirm any previous, voluntary, or accidental intake of cocaine.