中文摘要：

设计合成3种新型对称1,3-二正烷基咪唑六氟磷酸盐离子液体（[DCn-IM][PF6],n=4,5,8）.研究发现,离子液体热稳定性好,其憎水性和黏度随烷基碳原子数的增加而增加,但密度和极性却逐渐降低.以离子液体为顶空单滴萃取剂,分别考察了不同离子液体对5种酯类化合物的萃取性能.结果表明,离子液体的萃取率既受其黏度、憎水性和极性的影响,还与分析物本身的结构及性质密切相关.[DC4-IM][PF6]的萃取效率明显高于其他离子液体而被确定为萃取剂,并结合气质联用技术对萃取与分析条件进行优化.在0.36 g/mL NaCl溶液中,以1.0μL离子液体40℃萃取分析物35min后,250℃解吸1 min,得到富集倍数为260～1429,检出限为0.46～16.1μg/L.该方法应用于天然香料中5种酯类成分的同时测定,回收率为93.8%～108.9%,表明有高的灵敏度和准确性.

英文摘要：

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.