Australian Research Council Special Research Centre for Green Chemistry, School of Chemistry, Monash University, Melbourne, VIC 3800, Australia.
Department of Chemistry, San Jose State University, San Jose, CA 95192, USA.
Anal Chim Acta. 2015 Feb 15;859:79-86. doi: 10.1016/j.aca.2014.10.055. Epub 2014 Nov 3.
In this study, the zeta potentials of a silica hydride stationary phase (Diamond Hydride™) in the presence of different water-acetonitrile mixtures (from 0-80% (v/v) acetonitrile) of different ionic strengths (from 0-40mM) and pH values (from pH 3.0-7.0) have been investigated. Debye-Hückel theory was applied to explain the effect of changes in the pH and ionic strength of these aqueous media on the negative zeta potential of this stationary phase. The experimental zeta potentials of the Diamond Hydride™ particles as a function of acetonitrile content up to 50% (v/v) correlated (R(2)=0.998) with the predicted zeta potential values based on this established theory, when the values of the dissociation constant of all related species, as well as viscosity, dielectric constant and refractive index of the aqueous medium were taken into consideration. Further, the retention behavior of basic, acidic and neutral analytes was investigated under mobile phase conditions of higher pH and lower ionic strength. Under these conditions, the Diamond Hydride™ stationary phase surface became more negative, as assessed from the increasingly more negative zeta potentials, resulting in the ion exchange characteristics becoming more dominant and the basic analytes showing increasing retention. Ionic descriptors were derived from these chromatographic experiments based on the assumption that linear solvation energy relationships prevail. The results were compared with predicted ionic descriptors based on the different calculated zeta potential values resulting in an overall correlation of R(2)=0.888. These studies provide fundamental insights into the impact on the separation performance of changes in the zeta potential of the Diamond Hydride™ surface with the results relevant to other silica hydride and, potentially, to other types of stationary phase materials.
在这项研究中，研究了不同水-乙腈混合物（从 0-80%（v/v）乙腈）存在下硅氢化物固定相（Diamond Hydride™）的 ζ 电位，这些混合物的离子强度（从 0-40mM）和 pH 值（从 pH 3.0-7.0）不同。德拜-休克尔理论被应用于解释这些水介质的 pH 值和离子强度变化对该固定相负 ζ 电位的影响。当考虑到所有相关物种的离解常数、粘度、介电常数和水介质的折射率的值时，Diamond Hydride™颗粒的实验 ζ 电位作为乙腈含量的函数（高达 50%（v/v））与基于该建立理论预测的 ζ 电位值相关（R(2)=0.998）。此外，在更高 pH 值和更低离子强度的流动相条件下研究了碱性、酸性和中性分析物的保留行为。在这些条件下，从越来越负的 ζ 电位评估，Diamond Hydride™固定相表面变得更负，导致离子交换特性变得更加占主导地位，碱性分析物表现出越来越大的保留。基于线性溶剂化能量关系占主导地位的假设，从这些色谱实验中推导出了离子描述符。将结果与基于不同计算 ζ 电位值的预测离子描述符进行了比较，总体相关性为 R(2)=0.888。这些研究提供了对 Diamond Hydride™表面 ζ 电位变化对分离性能影响的基本见解，结果与其他硅氢化物相关，并且可能与其他类型的固定相材料相关。
