title: Determination of the interparticle void volume in packed beds via intraparticle Donnan exclusion.
abstract: 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.
authors.affiliation: Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Jung
authors.forename: Steffen
authors.initials: S
authors.lastname: Ehlert
authors.forename: Martin
authors.initials: M
authors.lastname: Pattky
authors.forename: Ulrich
authors.initials: U
authors.lastname: Tallarek
mesh_terms: D002850:Chromatography, Gel / Q000379:methods*; D002852:Chromatography, Ion Exchange / Q000379:methods*; D010316:Particle Size; D016062:Porosity; D012822:Silicon Dioxide / Q000737:chemistry; D055672:Static Electricity
chemical_list: D012822:Silicon Dioxide