Abstract：
Rosin-based chromatographic columns are widely used for separation purposes, but, to date, their phase ratios (Φ) have been imprecisely measured. This affects the understanding of their separation mechanism and the calculation of related thermodynamic parameters. In this study, a stationary phase was synthesized by bonding dehydroabietic acid (DA) to silica gel (Si-DO) and applied for reversed-phase liquid chromatography. The distribution coefficient (Kdm) of methyl dehydroabietate (MD), which has the same structure as the bonded phase of Si-DO, was used as a surrogate for the determination of the equilibrium coefficient (K) of Si-DO, and the Kdm values of MD in different mobile phases were measured and compared with the K values of Si-DO. It was found that the phase ratio of Si-DO varied with mobile phase composition and temperature, as shown by the Φ values: 0.039-0.122 for the methanol/water system and 0.051-0.116 for the acetonitrile/water system; in addition, the a indices were 0.552-0.757 and 0.564-0.674, respectively. The Kdm of MD was closer to the K of Si-DO than those of other surrogate models, including the octanol-water and octane-mobile phase partition coefficients. In addition, the thermodynamic parameters (ΔG°, ΔH°, and ΔS°) of n-alkylbenzenes on Si-DO were negative, indicating a spontaneous and enthalpy-driven separation process. Overall, the phase ratio of rosin-based columns is crucial for accurate thermodynamic analysis and interpretation of the separation mechanism. Finally, the MD surrogate model allows the estimation of phase ratio of Si-DO and other similar columns, providing a novel method for measuring the phase ratio of rosin-based columns and providing a validated concept and methodology for determining the phase ratios of HPLC columns.
摘要：
松香基色谱柱广泛用于分离目的，但是,到目前为止,它们的相位比(Φ)已经被不精确地测量。这影响了对它们分离机理的理解和相关热力学参数的计算。在这项研究中,通过将脱氢松香酸（DA）与硅胶（Si-DO）键合合成固定相，并将其用于反相液相色谱。脱氢松香酸甲酯(MD)的分配系数(Kdm),具有与Si-DO的键合相相同的结构，用作确定Si-DO平衡系数(K)的替代方法，测量了不同流动相中MD的Kdm值，并与Si-DO的K值进行了比较。发现Si-DO的相比例随流动相组成和温度而变化，如Φ值所示：甲醇/水系统为0.039-0.122，乙腈/水系统为0.051-0.116；此外，a指数分别为0.552-0.757和0.564-0.674。MD的Kdm比其他代理模型的Kdm更接近Si-DO的K，包括辛醇-水和辛烷-流动相分配系数。此外,热力学参数(ΔG°，ΔH°,Si-DO上的正烷基苯和ΔS°）为负，表明自发和焓驱动的分离过程。总的来说,松香柱的相比对于准确的热力学分析和分离机理的解释至关重要。最后,MD代理模型允许估计Si-DO和其他类似柱的相比，提供了一种测量松香柱相比的新方法，并提供了确定HPLC柱相比的有效概念和方法。
