Rapid analysis of caffeine in ‘‘smart drugs’’ and ‘‘energy drinks’’ by microemulsion electrokinetic chromatography (MEEKC) Eloisa Liotta a , Rossella Gottardo a , Catia Seri b , Claudia Rimondo b , Ivan Miksik c , Giovanni Serpelloni d , Franco Tagliaro a, * a Department of Public Health and Community Medicine, Unit of Forensic Medicine, University of Verona, Verona, Italy b National Early Warning System, Addiction Department, ULSS 20, Verona, Italy c Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic d Department of Anti-Drug Policies, Presidency of the Council of Ministers, Italy 1. Introduction Caffeine is the most ancient and widely consumed psychoactive drug, being naturally present in coffee and cacao beans, kola nuts, guarana berries, tea leaves etc. which are used worldwide in many cultures. The main effects of caffeine include physical endurance, reduction of fatigue and enhancement of mental alertness [1]. Because of its positive activity on the cardio-respiratory system and on the brain function, from year 1984 to year 2004 caffeine was included in the list of doping drugs, when detected in urine above 12 mg/mL. The physical and mental stimulation exerted by caffeine meets the modern trends of the young generations towards the use of ‘‘legal’’ stimulants, instead of the traditional but illegal cocaine and amphetamines. Also, it is noteworthy that caffeine availability has expanded since this compound is present as an additive in ‘‘energy drinks’’ and dietary supplements, often perceived as ‘‘safe’’, but not free from relevant adverse effects. Quite recently, different preparations containing caffeine (cap- sules, strips, powders) have become available through the Internet and in the so called ‘‘smart shops’’ as ‘‘legal’’, easily available stimulant drugs (smart drugs). In recent years, the use of alcohol in combination with caffeine- containing drinks or drugs has become fairly popular, for the ability of caffeine to offset the sedating effects of alcohol and to enhance alertness [2–4]. On the other hand, evidence of clinical syndromes of caffeine dependence and overdosing have been reported [5] as well as numerous caffeine-related intoxications and even deaths [6–9]. Current methods for caffeine analysis are based on: gas chromatography–mass spectrometry (GC–MS) [10,11] and HPLC–MS [12,13]. Unfortunately, these techniques are available only in specialized laboratories, but rarely in the laboratories of clinical chemistry and clinical toxicology, causing a clear underestimation of the phenomenon of caffeine abuse in the population. Because a higher versatility and easiness to switch between different analytical conditions, capillary electrophoresis (CE) may look preferable to the above mentioned techniques for the analysis Forensic Science International 220 (2012) 279–283 A R T I C L E I N F O Article history: Received 1 June 2011 Received in revised form 13 March 2012 Accepted 16 March 2012 Available online 11 April 2012 Keywords: Caffeine Energy drink Smart drug Microemulsion electrokinetic chromatography A B S T R A C T A novel method based on microemulsion electrokinetic chromatography (MEEKC) with diode array detection (DAD) for rapid determination of caffeine in commercial and clandestine stimulants, known as ‘‘energy drinks’’ and ‘‘smart drugs’’, is described. Separations were carried out in 50 cm  50 mm (ID) uncoated fused silica capillaries. The optimized buffer electrolyte was composed of 8.85 mM sodium tetraborate pH 9.5, SDS 3.3% (w/v), n-hexane 1.5% (v/v) and 1-butanol 6.6% (v/v). Separations were performed at a voltage of 20 kV. Sample injection conditions were 0.5 psi, 3 s. Diprofilline was used as internal standard. The determination of the analytes was based on the UV signal recorded at 275 nm, corresponding to the maximum wavelength of absorbance of caffeine, whereas peak identification and purity check was performed on the basis of the acquisition of UV radiation between 200 and 400 nm wavelengths. Under the described conditions, the separation of the compounds was achieved in 6 min without any interference from the matrix. Linearity was assessed within a caffeine concentration range from 5 to 100 mg/mL. The intra-day and inter-day precision values were below 0.37% for migration times and below 9.86% for peak areas. The present MEEKC method was successfully applied to the direct determination of caffeine in smart drugs and energy drinks. ß 2012 Elsevier Ireland Ltd. All rights reserved. * Corresponding author at: Department of Public Health and Community Medicine, Unit of Forensic Medicine, University of Verona, Policlinico, 37134 Verona, Italy. Tel.: +39 045 8124618; fax: +39 045 8027623. E-mail address: franco.tagliaro@univr.it (F. Tagliaro). Contents lists available at SciVerse ScienceDirect Forensic Science International jou r nal h o mep age: w ww.els evier .co m/lo c ate/fo r sc iin t 0379-0738/$ – see front matter ß 2012 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.forsciint.2012.03.015