Xiong Guohua, Goodridge Carolyn, Wang Limei, Chen Yong, Pawliszyn Janusz
Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1.
J Agric Food Chem. 2003 Dec 31;51(27):7841-7. doi: 10.1021/jf0346105.
Microwave-assisted headspace solid-phase microextraction (MA-HS-SPME) was developed as a simple and effective method for fast sampling of volatile organic compounds (VOCs) from Eucalyptus citriodora Hook (E. citriodora) leaves. During microwave heating, a simple shielding device made of aluminum foil was used to protect the SPME fiber from microwave irradiation while allowing the sample to be heated. A room temperature water bath was also used to allow microwave heating to be conducted in a more controlled manner. The inner heating caused by microwave irradiation dramatically accelerated the emission of VOCs from the sample, but no marked change in headspace temperature in the sample vial was found. Under optimum conditions, the extraction efficiencies obtained with microwave heating were much higher than those obtained without microwave heating for all fibers used, namely, 7-microm polydimethylsiloxane (PDMS), 100-microm polydimethylsiloxane (PDMS), 65-microm polydimethylsiloxane/divinylbenzene (PDMS/DVB), and 75-microm carboxen/polydimethylsiloxane (CAR/PDMS). The improvement of extraction efficiency using MA-HS-SPME allowed more VOC events to be detected, with more balanced extraction of VOCs of lower and higher molecular masses. Moreover, a good linear relationship was found between sample size and GC-FID response (total peak area of VOCs), indicating the usefulness of MA-HS-SPME for quantitative analysis of individual volatile compounds in E. citriodora leaves.
微波辅助顶空固相微萃取（MA-HS-SPME）被开发为一种从柠檬桉（E. citriodora）叶片中快速采样挥发性有机化合物（VOCs）的简单有效方法。在微波加热过程中，使用一种由铝箔制成的简单屏蔽装置来保护固相微萃取纤维免受微波辐射，同时允许样品被加热。还使用了室温水浴，以使微波加热能以更可控的方式进行。微波辐射引起的内部加热极大地加速了样品中VOCs的释放，但未发现样品瓶顶空温度有明显变化。在最佳条件下，对于所有使用的纤维，即7微米聚二甲基硅氧烷（PDMS）、100微米聚二甲基硅氧烷（PDMS）、65微米聚二甲基硅氧烷/二乙烯基苯（PDMS/DVB）和75微米碳分子筛/聚二甲基硅氧烷（CAR/PDMS），微波加热获得的萃取效率远高于无微波加热时获得的萃取效率。使用MA-HS-SPME提高萃取效率后，能够检测到更多的VOC事件，对低分子量和高分子量VOCs的萃取更加均衡。此外，在样品量与气相色谱 - 火焰离子化检测器响应（VOCs的总峰面积）之间发现了良好的线性关系，表明MA-HS-SPME可用于柠檬桉叶片中单个挥发性化合物的定量分析。
