製備 Silprbipy 離子液體靜相管柱應用於超臨界流體層析分離酸中鹼性物質之研究

Preparation and Application of Surface-confined Ionic Liquid Silprbipy to Separate Acidic, Basic and Neutral Compounds under Supercritical Fluid Chromatography

洪郁琇(Yu-Siou Hung)

指導教授 ： 魏國佐

國立中正大學/理學院/化學暨生物化學系/碩士(2013年)

摘要

近年來離子液體 (ionic liquid，IL) 在綠色化學中扮演了重要的角色，由於IL擁有了高熱穩定性、高導電度、低熔點及低的蒸氣壓的特性，因而被視為一種綠色溶劑，在學術上離子液體已用於萃取、液相層析、毛細管電泳、電化學等領域。
本研究將4,4-bipyridine化學鍵結在silica上成Silprbipy，並在Silprbipy的N端接上三種不同官能機合成出4種含4,4-bipyridine 官能基的離子液體靜相靜相，將其應用於超臨界流體層析 (Supercritical Fluid Chromatography, SFC) 分離。
SFC分離探討時改變有機溶劑添加量、管柱壓力、及管柱溫度得到最佳分離條件後，實驗結果顯示四支管柱均可成功分離酸、中、與鹼性化合物，分析檢量線 R2 均大於0.9903，偵測極限可達0.014 ppm。而後四支管柱在相同條件下分離酸中鹼性化合物，並利用線性溶解度能量關係式Linear solvation energy relationship (LSER) model 探討管柱靜相分子架構與作用力的關聯性。
在許多層析管柱製備中，最後都會做end-cap之步驟是希望能避免管柱表面的矽醇基而造成peak拖尾現象，但end-cap步驟並無法把所有的矽醇機給遮蔽，因此我們在動相中加入水，使管柱吸附一層薄薄的水層，以探討水層的吸附對矽醇基的遮蔽性；實驗結果顯示，有end-cap的管柱由於矽醇基的減少，使層析波峰對稱性確實比沒有end-cap的管柱較好；另外水層的吸附，也明顯的改善沒有end-cap管柱的層析波峰對稱性。
在SFC系統中，因動相使用非極性超臨界CO2，因此對於分離高水溶性分析物較為困難。本實驗結果顯示Silprbipy離子液體管柱可成功的分離四種高水溶性離子液體及其前驅物，分析校正曲線的線性相關係數 (R2) 達 0.9929，且偵測極限可達 1.04 ppm，並應用離子液體分析檢測 IL 在不同溶劑中的分配係數。

關鍵字

離子液體 ； 靜相

並列摘要

Because ionic liquid (IL) has several unique properties, such as high thermal stability, high conductivity, low melting point, and low vapor pressure characteristics, IL is considered as a green solvent. Ionic liquids (ILs) have been playing important roles in many fields. In separation, ILs have been applied to solvent extractions, liquid chromatography, capillary electrophoresis, etc.
In this study, 4,4-bipyridine was bounded to silica surface to form Silprbipy, then the N-terminal was further connected with three different functional structures to form 4,4-bipyridine containing ionic liquid stationary phases. Their SFC separation performances were then evaluated.
All these columns successfully separate acidic, basic and neutral compounds at optimized conditions. The experimental results show that the correlation coefficients (R2) of the calibration curve are greater than 0.9903, the detection limits were up to 0.014 ppm. These stationary phases were characterized with the model of LSER under the same conditions for the separations of acidic, basic, and neutral compounds.
In chromatographic column preparation, an end-cap is essential to reduce the surface silanol that causes peak tailing. However, the end-cap procedure cannot mask all silanol groups. Since adding water to the mobile phase can form a thin layer on the silica surface by surface adsorption, the water layer may play the role of masking the silanol activity. Such that, the end-capping procedure can be avoid to simplified the column preparation. The results show that peak asymmetry factors from end-capped column are better than those of none end-caped. Nevertheless, adding water to none end-cap column did improve the peak asymmetry factor. Therefore the silanol seems to bury in the water layer of silica gel.
In a CO2 SFC, the separation of highly polar solutes is a difficulttask and has attracted wide interests, due to the importance of these compounds in pharmaceutical industry. To demonstrate the potential of IL columns, Silprbipy was employed to separate the mixture of four ionic liquids and one precursor. The mixture was completely separated with linear correlation coefficient (R2) better than 0.9929, and the detection limit up to 1.04 ppm. These results clearly indicates the potential of this new type of stationary phase in SFC separations.

並列關鍵字

stationary phase ； ionic liquid

參考文獻

(6) Reyna-González, J. M.; Galicia-Pérez, R.; Reyes-López, J. C.; Aguilar-Martínez, M. Sep. Purif. Technol. 2012, 89, 320.

(8) Tian, K.; Wang, Y.; Chen, Y.; Chen, X.; Hu, Z. Talanta 2007, 72, 587.

(2) Seddon, K. R. S., A.; Torres, M.-J. Pure Appl. Chem. 2000, 72, 2275.

(4) Welton, T. Chem. Rev. 1999, 99, 2071.

(5) Earle, M. J.; Seddon, K. R. Pure Appl. Chem. 2000, 72, 1391.