Department of Chemistry, Faculty of Science, University of Tehran, Tehran, Iran.
J Chromatogr A. 2013 Mar 8;1280:1-8. doi: 10.1016/j.chroma.2013.01.029. Epub 2013 Jan 16.
Ultrasound assisted extraction (UAE) followed by dispersive liquid-liquid microextraction (DLLME) was used for extraction and preconcentration of volatile constituents of six tea plants. The preconcentrated compounds were analyzed by gas chromatography-mass spectrometry (GC-MS). Totally, 42 compounds were identified and caffeine was quantitatively determined. The main parameters (factors) of the extraction process were optimized by using a central composite design (CCD). Methanol and chloroform were selected as the extraction solvent and preconcentration solvent, respectively .The optimal conditions were obtained as 21 in for sonication time; 32°C for temperature; 27 L for volume of extraction solvent and 7.4% for salt concentration (NaCl/H(2)O). The determination coefficient (R(2)) was 0.9988. The relative standard deviation (RSD %) was 4.8 (n=5), and the enhancement factors (EFs) were 4.0-42.6.
超声辅助提取（UAE）后，分散液-液微萃取（DLLME）用于提取和浓缩六种茶树的挥发性成分。浓缩的化合物通过气相色谱-质谱法（GC-MS）进行分析。总共鉴定出 42 种化合物，并定量测定了咖啡因。通过使用中心组合设计（CCD）优化了萃取过程的主要参数（因素）。甲醇和氯仿分别被选为萃取溶剂和浓缩溶剂。最佳条件为超声时间 21 分钟；温度 32°C；萃取溶剂体积 27 L；盐浓度（NaCl/H2O）为 7.4%。测定系数（R2）为 0.9988。相对标准偏差（RSD%）为 4.8（n=5），增强因子（EFs）为 4.0-42.6。
