期刊
JOURNAL OF CHROMATOGRAPHY A
卷 1280, 期 -, 页码 1-8出版社
ELSEVIER
DOI: 10.1016/j.chroma.2013.01.029
关键词
Tea; Caffeine; Ultrasonic-assisted extraction; Dispersive liquid-liquid microextraction; Gas chromatography; Central composite design
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 min for sonication time; 32 degrees C for temperature; 27 mu L for volume of extraction solvent and 7.4% for salt concentration (NaCl/H2O). 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. (c) 2013 Elsevier B.V. All rights reserved.
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