Structure-function relationships in high-density docosylsilane bonded stationary phases by Raman spectroscopy and comparison to octadecylsilane bonded stationary phases: Effects of aromatic compounds

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• 作者：Zhaohui Liao ; Jeanne E. Pemberton
• 关键词：RPLC ; Alkyl chain stationary phase conformational order ; Stationary phase– ; solvent interactions ; Raman spectroscopy ; Aromatic solvent
• 刊名：Journal of Chromatography A
• 出版年：2008
• 出版时间：6 June 2008
• 年：2008
• 卷：1193
• 期：1-2
• 页码：60-69
• 全文大小：2264 K

文摘

The effects of four aromatic compounds on alkyl chain conformational order for a series of high-density docosylsilane (C22) stationary phases with surface coverage ranging from 3.61 to 6.97 μmol/m² are investigated using Raman spectroscopy. Aromatic compounds studied include benzene-d₆, toluene-d₈, aniline-d₇ and anisole-d₈. In general, these aromatic solvents decrease the conformational order of the C22 phases relative to air suggesting partitioning of the aromatics into the alkyl chains of these stationary phases. Changes in alkyl chain conformational order are linearly dependent on the solvent hydrophobicity parameter, log K_ow, and are also dependent on stationary phase properties (i.e. polymerization method and surface coverage). A comparison is made between C22 and C18 bonded phase systems. The conformational order of the alkyl chains in a mixed solute/mobile phase system is also studied using 80 % methanol/water as the mobile phase and aniline-d₇, anisole-d₈ or toluene-d₈ as solutes. Collectively, the Raman spectroscopic evidence at the molecular level suggests interaction of these aromatic species with the bonded alkyl chains through partitioning.