Internal structures of wide-pore packing materials for high-performance liquid chromatography studied by transmission electron microscopy

• Published in: Journal of Chromatography A 1988, Vol.448 (1), p.95-108
• Main Authors: Tanaka, Nobuo, Hashidzume, Katsushi, Araki, Mikio, Tsuchiya, Hajime, Okuno, Akitoshi, Iwaguchi, Kazufusa, Ohnishi, Seiichiro, Takai, Nobuharu
• Format: Article
• Language: English
• Subjects: Analytical chemistry; Chemistry; Chromatographic methods and physical methods associated with chromatography; Exact sciences and technology; Other chromatographic methods
• ISSN: 0021-9673
• DOI: 10.1016/S0021-9673(01)84568-4

Internal structures of high-performance liquid chromatographic column packing materials, including porous glass particles, silica gels and polymer gels, were studied by transmission electron microscopy. Clear micrographs of the internal structures were obtained for macroporous particles by using ultrathin sections, with staining in the case of polymer gels. Corpuscular structures were seen with silica gels with relatively small pores, while porous glass particles showed a typical spongy structure. Spherical silica particles with large pores in the range 50–500 nm from different sources possess common spongy structures with a difference in the presence of a shell at the outer surface. Several silica packing materials of 30–400 nm nominal pore size were found to be mixtures of two or more kinds of silica particles of different pore sizes, which accounted for the broad, in some instances bimodal, pore size distribution found in nitrogen adsorption measurements and in inverse size-exclusion chromatography. A bimodal pore size distribution was also seen for unmixed macroporous polymer gel particles, with one of the maxima in a small pore size range, presumably due to the presence of micropores formed by the network structures in microgels.