Department of Public Health and Community Medicine, Unit of Forensic Medicine, University of Verona, Verona, Italy.
Forensic Sci Int. 2012 Jul 10;220(1-3):279-83. doi: 10.1016/j.forsciint.2012.03.015. Epub 2012 Apr 11.
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 μm (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 μg/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.
一种基于微乳液电动色谱（MEEKC）与二极管阵列检测（DAD）的新方法，用于快速测定商业和秘密兴奋剂中咖啡因的含量，这些兴奋剂被称为“能量饮料”和“聪明药”。分离在 50 cm×50 μm（内径）未涂层熔融石英毛细管中进行。优化的缓冲电解质由 8.85 mM 硼酸钠 pH 9.5、SDS 3.3%（w/v）、正己烷 1.5%（v/v）和 1-丁醇 6.6%（v/v）组成。分离在 20 kV 的电压下进行。样品进样条件为 0.5 psi、3 s。双非利林被用作内标。分析物的测定是基于在 275 nm 处记录的紫外信号，这对应于咖啡因的最大吸收波长，而峰的识别和纯度检查是基于在 200 到 400nm 波长范围内获取的紫外辐射进行的。在所描述的条件下，化合物在 6 分钟内无需任何基质干扰即可分离。在 5 至 100μg/mL 的咖啡因浓度范围内进行了线性评估。日内和日间精密度值的迁移时间低于 0.37%，峰面积低于 9.86%。本 MEEKC 方法成功应用于直接测定聪明药和能量饮料中的咖啡因。
