Journal of Chromatography B, 751 (2001) 19–27 www.elsevier.com / locate / chromb Analysis of cocaethylene, benzoylecgonine and cocaine in human urine by high-performance thin-layer chromatography with ultraviolet detection: a comparison with high-performance liquid chromatography * Letizia Antonilli , Carmen Suriano, Maria Caterina Grassi, Paolo Nencini ` Dipartimento di Fisiologia Umana e Farmacologia and Servizio Speciale Antidroga, Universita di Roma ‘ La Sapienza’, P .le A. Moro 5, 00185 Rome, Italy Received 10 May 2000; received in revised form 11 July 2000; accepted 2 August 2000 Abstract Cocaine and ethanol are frequently used at the same time, resulting in the formation of cocaethylene by transesterification. We studied the capability of high-performance thin-layer chromatography (HPTLC) to simultaneously detect cocaethylene, cocaine and benzoylecgonine in 16 urine specimens of drug addicts, previously tested as positive for benzoylecgonine at immunoenzymatic screening. Accuracy and precision, as well as detection and quantitation limits of the method, were evaluated by comparison with high-performance liquid chromatography (HPLC). HPTLC limit of quantitation was 1.0 mg / ml for the three compounds, whereas HPLC limits were 0.2 mg / ml for benzoylecgonine and cocaine, and 0.1 mg/ml for cocaethylene. The relative standard deviation (RSD) ranged from 1.03 to 12.60% and from 1.56 to 16.6% for intra- and inter-day HPTLC analysis, respectively. In the case of the HPLC method, the RSD for the intra-day precision ranged from 0.79 to 5.05%, whereas it ranged from 1.19 to 10.64% for the inter-day precision. In comparison with HPLC, HPTLC is less expensive and faster, requiring 2–3 h to analyze 10–12 samples on a single plate. In conclusion, HPTLC is suitable for determinations of the three analytes only for samples with high concentrations.  2001 Elsevier Science B.V. All rights reserved. Keywords: Cocaethylene; Benzoylecgonine; Cocaine 1. Introduction microsomal carboxylesterases [3,4]. This metabolite preserves many of the pharmacological effects of In humans cocaine is extensively hydrolyzed to cocaine and shows a longer elimination half-life (i.e., benzoylecgonine and to ecgonine methyl ester or is 148 vs. 83 min) [5]. Pharmacological effects of n-demethylated to norcocaine [1,2]. However, when cocaethylene may then account for the habit of many taken in combination with ethanol, a substantial cocaine abusers to take the drug in combination with amount of cocaine is converted to cocaethylene by a ethanol consumption [6,7]. reaction of transesterification mediated by hepatic As far as it proves the co-ingestion of cocaine and ethanol, searching for cocaethylene in urine is there- *Corresponding author. Fax: 139-6-4991-2497. fore of clinical interest [8]. Unfortunately, so far 0378-4347 / 01 / $ – see front matter  2001 Elsevier Science B.V. All rights reserved. PII: S0378-4347(00)00445-X