Department of Applied Chemistry and Biochemistry, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan.
Anal Chim Acta. 2012 Aug 13;738:95-101. doi: 10.1016/j.aca.2012.06.018. Epub 2012 Jun 18.
In this paper, a new imidazolium-embedded C(18) stationary phase (SiImC(18)) for reversed-phase high-performance liquid chromatography is described. 1-Allyl-3-octadecylimidazolium bromide ionic liquid compound having a long alkyl chain and reactive groups was newly prepared and grafted onto 3-mercaptopropyltrimethoxysilane-modified silica via a surface-initiated radical-chain transfer addition reaction. The SiImC(18) obtained was characterized by elemental analysis, infrared spectroscopy, thermogravimetric analysis, diffuse reflectance infrared Fourier transform, and solid-state (13)C and (29)Si cross-polarization/magic angle spinning nuclear magnetic resonance spectroscopy. The selectivity toward polycyclic aromatic hydrocarbons relative to that toward alkylbenzenes exhibited by SiImC(18) was higher than the corresponding selectivity exhibited by a conventional octadecyl silica (ODS) column, which could be explained by electrostatic π-π interaction cationic imidazolium and electron-rich aromatic rings. On the other hand, SiImC(18) also showed high selectivity for polar compounds, which was based on the multiple interaction and retention mechanisms of this phase with different analytes. 1,6-Dinitropyrene and 1,8-dinitropyrene, which form a positional isomer pair of dipolar compounds, were separated successfully with the SiImC(18) phase. Seven nucleosides and bases (i.e. cytidine, uracil, uridine, thymine, guanosine, xanthosine, and adenosine) were separated using only water as the mobile phase within 8min, which is difficult to achieve when using conventional hydrophobic columns such as ODS. The combination of electrostatic and hydrophobic interactions is important for the effective separation of such basic compounds without the use of any organic additive as the eluent in the octadecylimidazolium column.
本文描述了一种用于反相高效液相色谱的新型咪唑嵌入 C(18)固定相（SiImC(18)）。新制备了具有长烷基链和反应性基团的 1-烯丙基-3-十八烷基咪唑溴盐离子液体化合物，并通过表面引发自由基链转移加成反应接枝到 3-巯丙基三甲氧基硅烷修饰的硅胶上。通过元素分析、红外光谱、热重分析、漫反射红外傅里叶变换、固态（13）C 和（29）Si 交叉极化/魔角旋转核磁共振光谱对所得的 SiImC(18)进行了表征。与常规的十八烷基硅烷（ODS）柱相比，SiImC(18)对多环芳烃的选择性高于烷基苯，这可以通过静电 π-π 相互作用阳离子咪唑和富电子芳环来解释。另一方面，SiImC(18)对极性化合物也表现出高选择性，这是基于该相与不同分析物的多种相互作用和保留机制。成功地用 SiImC(18)相分离了 1,6-二硝基芘和 1,8-二硝基芘这一对偶极化合物的位置异构体。只用水作为流动相，在 8min 内就可以分离七种核苷和碱基（即胞嘧啶、尿嘧啶、尿苷、胸腺嘧啶、鸟苷、黄嘌呤核苷和腺苷），这在使用常规疏水性柱（如 ODS）时很难实现。在十八烷基咪唑柱中，不使用任何有机溶剂作为洗脱剂，静电和疏水相互作用的结合对于有效分离此类碱性化合物非常重要。
