Reta M, Carr P W, Sadek P C, Rutan S C
Department of Chemistry, University of Minnesota, Minneapolis 55455, USA.
Anal Chem. 1999 Aug 15;71(16):3484-96. doi: 10.1021/ac990081l.
The retention properties of eight alkyl, aromatic, and fluorinated reversed-phase high-performance liquid chromatography bonded phases were characterized through the use of linear solvation energy relationships (LSERs). The stationary phases were investigated in a series of methanol/water mobile phases. LSER results show that solute molecular size and hydrogen bond acceptor basicity under all conditions are the two dominant retention controlling factors and that these two factors are linearly correlated when either different stationary phases at a fixed mobile-phase composition or different mobile-phase compositions at a fixed stationary phase are considered. The large variation in the dependence of retention on solute molecular volume as only the stationary phase is changed indicates that the dispersive interactions between nonpolar solutes and the stationary phase are quite significant relative to the energy of the mobile-phase cavity formation process. PCA results indicate that one PCA factor is required to explain the data when stationary phases of the same chemical nature (alkyl, aromatic, and fluoroalkyl phases) are individually considered. However, three PCA factors are not quite sufficient to explain the whole data set for the three classes of stationary phases. Despite this, the average standard deviation obtained by the use of these principal component factors are significantly smaller than the average standard deviation obtained by the LSER approach. In addition, selectivities predicted through the LSER equation are not in complete agreement with experimental results. These results show that the LSER model does not properly account for all molecular interactions involved in RP-HPLC. The failure could reside in the V2 solute parameter used to account for both dispersive and cohesive interactions since "shape selectivity" predictions for a pair of structural isomers are very bad.
通过线性溶剂化能关系（LSER）对8种烷基、芳香基和氟化反相高效液相色谱键合相的保留特性进行了表征。在一系列甲醇/水流动相中对固定相进行了研究。LSER结果表明，在所有条件下溶质分子大小和氢键受体碱性是两个主要的保留控制因素，并且当考虑固定流动相组成下的不同固定相或固定固定相下的不同流动相组成时，这两个因素呈线性相关。仅改变固定相时保留对溶质分子体积依赖性的巨大变化表明，相对于流动相空穴形成过程的能量，非极性溶质与固定相之间的分散相互作用相当显著。主成分分析（PCA）结果表明，单独考虑相同化学性质的固定相（烷基、芳香基和氟烷基相）时，需要一个PCA因子来解释数据。然而，三个PCA因子不足以解释这三类固定相的整个数据集。尽管如此，使用这些主成分因子获得的平均标准差明显小于通过LSER方法获得的平均标准差。此外，通过LSER方程预测的选择性与实验结果不完全一致。这些结果表明，LSER模型没有正确考虑反相高效液相色谱中涉及的所有分子相互作用。失败可能在于用于解释分散和内聚相互作用的V2溶质参数，因为对一对结构异构体的“形状选择性”预测非常差。
