Hawthorne S B, Miller D J, Pawliszyn J, Arthur C L
Energy and Environmental Research Center, University of North Dakota, Grand Forks 58202.
J Chromatogr. 1992 Jun 19;603(1-2):185-91. doi: 10.1016/0021-9673(92)85360-6.
Caffeine concentrations in beverages were determined using a simple and rapid method based on microextraction of caffeine onto the surface of a fused-silica fiber. The uncoated fiber was dipped into the beverage sample for 5 min after the addition of isotopically labeled (trimethyl 13C)caffeine. The adsorbed caffeine was then thermally desorbed in a conventional split/splitless injection port, and the concentration of caffeine was determined using gas chromatography with mass spectrometric detection. Quantitative reproducibilities were ca. 5% (relative standard deviation) and the entire scheme including sample preparation and gas chromatographic analysis was completed in ca. 15 min per sample. The potential of the microextraction technique for the analysis of flavor and fragrance compounds in non-caffeinated beverages is also demonstrated. Since no solvents or class-fractionation steps are required, the method has good potential for automation.
采用一种基于将咖啡因微萃取至熔融石英纤维表面的简单快速方法测定饮料中的咖啡因浓度。在加入同位素标记的（三甲基13C）咖啡因后，将未涂层的纤维浸入饮料样品中5分钟。然后将吸附的咖啡因在传统的分流/不分流进样口中进行热解吸，并使用气相色谱 - 质谱检测法测定咖啡因的浓度。定量重现性约为5%（相对标准偏差），每个样品包括样品制备和气相色谱分析在内的整个流程约在15分钟内完成。还展示了微萃取技术用于分析无咖啡因饮料中风味和香料化合物的潜力。由于无需使用溶剂或分级分离步骤，该方法具有良好的自动化潜力。
