Departament de Química Analítica i Institut de Biomedicina, Universitat de Barcelona, Martí i Franquès 1-11, 08028 Barcelona, Spain.
Departament de Química Analítica i Institut de Biomedicina, Universitat de Barcelona, Martí i Franquès 1-11, 08028 Barcelona, Spain; Serra Húnter Programme, Generalitat de Catalunya, 08002 Barcelona, Spain.
J Chromatogr A. 2021 Jan 4;1635:461720. doi: 10.1016/j.chroma.2020.461720. Epub 2020 Nov 14.
The LFER model of Abraham is applied to the retention of the neutral and ionic forms of 94 solutes in a C18 column and 40% v/v acetonitrile/water mobile phase. The results show that polarizability and cavity formation interactions increase retention, whereas dipole and hydrogen bonding interactions favours partition to the mobile phase and thus, they decrease retention. The coefficients of the ionic descriptors measure the effect of the electrostatic interactions and their contribution to partition of the cation or anion between the two mobile and stationary chromatographic phases. A new LFER model for application to the retention of partially dissociated acids and bases is derived averaging the descriptors of the neutral and ionic forms according to their degrees of ionization in the mobile phase. This new LFER model is satisfactorily compared to other literature modified Abraham models for a set of 498 retention data of partially dissociated acids and bases. All tested models require the calculation of the ionization degrees of the compounds at the measuring pH. Calculation of the ionization degrees in the chromatographic mobile phase (i.e. from pH and pK in the eluent) give good correlations for all tested models. However, estimation of these ionization degrees from pH - pK data in pure water gives biased estimations of the retention of the partially ionized solutes.
Abraham 的 LFER 模型被应用于在 C18 柱和 40%v/v 乙腈/水流动相中保留 94 种中性和离子形式的溶质。结果表明，极化率和空穴形成相互作用增加保留，而偶极和氢键相互作用有利于向流动相分配，因此它们降低保留。离子描述符的系数衡量静电相互作用的影响及其对阳离子或阴离子在两个流动和固定相之间分配的贡献。根据在流动相中的离解度，通过平均中性和离子形式的描述符，推导出了一种适用于部分离解酸和碱保留的新 LFER 模型。与其他文献中修改的 Abraham 模型相比，该新 LFER 模型对 498 个部分离解酸和碱的保留数据进行了满意的比较。所有测试的模型都需要在测量 pH 值时计算化合物的离解度。在色谱流动相中（即在洗脱液中的 pH 和 pK 值）计算离解度可以为所有测试的模型提供良好的相关性。然而，从纯水中的 pH-pK 值数据估计这些离解度会导致对部分离解溶质保留的有偏差估计。
