### 对称烷基咪唑离子液体单滴微萃取-气质联用测定天然香料中酯类成分

1. a 江南大学食品胶体与生物技术教育部重点实验室 无锡 214122;
b 江南大学化学与材料工程学院 无锡 214122
• 投稿日期:2012-04-30 发布日期:2012-06-04
• 通讯作者: 李在均
• 基金资助:

项目受国家自然科学基金(No. 21176101)、国家科技支撑计划(No. 2011BAK10B00)、浙江省自然科学基金(No. Y407321)和江苏省“青蓝工程”资助.

### Symmetrical 1,3-Dialkylimidazolium Ionic Liquid Based Single-Drop Microextraction Coupled to GC-MS for the Determination of Esters in Natural Flavors

Li Minga,b, Li Zaijuna,b, Li Guanyanb, Chen Linjieb, Wang Linab, Jiang Cuicuib, Li Lulub, Zhang Zhuangtaib

1. a The Key Laboratory of Food Colloids and Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122;
b School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122
• Received:2012-04-30 Published:2012-06-04
• Supported by:

Project supported by the National Natural Science Foundation of China (No. 21176101), National Key Technology R & D Program (No. 2011BAK10B00), the Natural Science Foundation of Zhejiang Province (No. Y407321), and the Qing Lan Project of Jiangsu Province.

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.