Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany.
J Chromatogr A. 2010 Jan 29;1217(5):696-704. doi: 10.1016/j.chroma.2009.12.010. Epub 2009 Dec 5.
Interparticle void volumes and porosities of packed capillaries have been determined using intraparticle Donnan exclusion of a small, unretained, co-ionic tracer (nitrate ions). The operational domain of this approach has been characterized for bare silica, reversed-phase, and strong cation-exchange materials (with different particle sizes and intraparticle pore sizes) in dependence of the mobile phase ionic strength. Interparticle porosities agree well with those analyzed by inverse size-exclusion chromatography (ISEC). Limitations to the use of Donnan exclusion (electrostatic exclusion) and ISEC (mechanical exclusion) arise as either type of exclusion becomes noticeable also in the cusp regions between the particles, or as the intraparticle pores are so large that complete electrostatic and size-exclusion are difficult to realize. Our data confirm that intraparticle Donnan exclusion presents a most simple, fast, and reliable approach for the analysis of packing densities.
已使用小的、未保留的同离子示踪剂（硝酸盐离子）在颗粒内的 Donnan 排除来确定填充毛细管的颗粒间空隙体积和孔隙率。已根据流动相离子强度对该方法的作用范围进行了描述，用于裸二氧化硅、反相和强阳离子交换材料（具有不同的颗粒大小和颗粒内孔径）。颗粒间孔隙率与通过反尺寸排阻色谱（ISEC）分析的结果非常吻合。Donnan 排除（静电排除）和 ISEC（机械排除）的使用受到限制，因为这两种类型的排除都在颗粒之间的峰区变得明显，或者因为颗粒内的孔太大，使得完全的静电和尺寸排阻难以实现。我们的数据证实，颗粒内的 Donnan 排除为分析填充密度提供了一种最简单、最快和最可靠的方法。
