Three novel symmetrical 1,3-dialkylimidazolium ionic liquids ([DCn-IM][PF6], n＝4, 5, 8) were designed and synthesized in the laboratory. The research revealed that all the symmetrical ionic liquids studied exhibit excellent thermal stability. Besides, the hydrophobicity and viscosity of the ionic liquid increase and its density and polarity decrease with the increase of the alkyl chain length in the imidazole ring. To investigate the extraction performance of different ionic liquid for five esters flavors, the ionic liquid was chosen as the extractant for headspace single-drop microextraction (HS-SDME) in this study. The results showed that the extraction efficiency depend not only on the viscosity, hydrophobicity and polarity of the ionic liquid, but also on the structure and properties of the analyte. Since the ionic liquid 1,3-di-n-butylimidazolium hexafluorophosphate abbreviated as [DC4-IM][PF6] offers obviously better extraction efficiency than other ionic liquids, it was selected as headspace drop. Moreover, experimental parameters for the extraction and analysis were also optimized based on the coupling with gas chromatography-mass spectrometry. Under optimal conditions, i.e. the headspace volume of [DC4-IM][PF6] 1.0 μL, the concentration of salt 0.36 g/mL , reaction temperature of 40 ℃, reaction time 35 min and desorption 1 min at 250 ℃, the enrichment factors and detection limits were in the range of 260—1429 and 0.46—16.1 μg/L for the five esters, respectively. This method has been applied to simultaneous determination of five esters in natural flavors such as rose oil, rose absolute and jasmin absolute, and the recoveries of standard additives varied in the range of 93.8%—108.9%. The fact confirmed that the proposed method is of high sensitivity and good precision.
Li Ming
,
Li Zaijun
,
Li Guanyan
,
Chen Linjie
,
Wang Lina
,
Jiang Cuicui
,
Li Lulu
,
Zhang Zhuangtai
. Symmetrical 1,3-Dialkylimidazolium Ionic Liquid Based Single-Drop Microextraction Coupled to GC-MS for the Determination of Esters in Natural Flavors[J]. Acta Chimica Sinica, 2012
, 70(15)
: 1625
-1630
.
DOI: 10.6023/A12040155
[1] Sun, B. G.; He, J. In Chemistry and Technology of Perfumes, 2nd ed., Chemical Industry Press, Beijing, 2004, p. 249. (孙宝国, 何坚, 香料化学与工艺学(第二版), 化学工业出版社, 北京, 2004, p. 249.)
[2] Li, M.; Wang, P. Y.; Tian, H. X. Basic Applications of Flavors and Fragrances, China Textile & Apparel Press, Beijing, 2010, p. 118, 84, 76. (李明, 王培义, 田怀香, 香料香精应用基础, 中国纺织出版社, 北京, 2010, p. 118, 84, 76.)
[3] Bicchi, C.; Rubiolo, P.; Cordero, C. Anal. Bioanal. Chem. 2006, 384, 53.
[4] Liu, H.; Dasgupta, P. K. Anal. Chem. 1996, 68, 1817.
[5] Jeannot, M. A.; Cantwell, F. F. Anal. Chem. 1996, 68, 2236.
[6] Przyjazny, A.; Kokosa, J. M. J. Chromatogr. A 2002, 977, 143.
[7] Theis, A. L.; Waldack, A. J.; Hansen, S. M.; Jeannot, M. A. Anal. Chem. 2001, 73, 5651.
[8] Tankeviciute, A.; Kazlauskas, R.; Vickackaite, V. Analyst 2001, 126, 1674.
[9] Liu, J. F.; Jiang, G. B.; Chi, Y. G.; Cai, Y. Q.; Zhou, Q. X.; Hu, J. T. Anal. Chem. 2003, 75, 5870.
[10] Liu, J. F.; Chi, Y. G.; Jiang, G. B.; Tai, C.; Peng, J. F.; Hu, J. T. J. Chromatogr. A 2004, 1026, 143.
[11] Liu, J. F.; Jönsson, J. Å.; Jiang, G. B. Trends Anal. Chem. 2005, 24, 20.
[12] Aguilera-Herrador, E.; Lucena, R.; Cardenas, S.; Valcarcel, M. J. Chromatogr. A 2009, 1201, 106.
[13] Chisvert, A.; Roman, I. P.; Vidal, L.; Canals, A. J. Chromatogr. A 2009, 1216, 1290.
[14] Zhao, H.; Xia, S.-Q.; Ma, P.-S. J. Chem. Technol. Biotechnol. 2005, 80, 1089.
[15] Anderson, J. L.; Armstrong, D. W.; Wei, G. T. Anal. Chem. 2006, 78, 2892.
[16] Fan, J.; Fan, Y. C.; Wang, J. J.; Cui, F. L. Acta Chim. Sinica 2006, 64, 1455. (樊静, 范云场, 王键吉, 崔凤灵, 化学学报, 2006, 64, 1455.)
[17] Zhao, F. Q.; Li, J.; Zeng, B. Z. Chin. J. Anal. Chem. 2009, 37, 939. (赵发琼, 李晶, 曾百肇, 分析化学, 2009, 37, 939.)
[18] Yao, C.; Twu, P.; Anderson, J. L. Chromatographia 2010, 72, 393. Reichardt, C. Green Chem. 2005, 7, 339.
