Anion exchange silica monolith for capillary liquid chromatography

Abstract

An anion exchange monolithic silica capillary column was prepared by surface modification of a hybrid monolithic silica capillary column prepared from a mixture of tetramethoxysilane (TMOS) and methyltrimethoxysilane (MTMS). The surface modification was carried out by on-column copolymerization of N-[3-(dimethylamino)propyl]acrylamide methyl chloride-quaternary salt (DMAPAA-Q) with 3-methacryloxypropyl moieties bonded as an anchor to the silica surface to form a strong anion exchange stationary phase. The columns were examined for their performance in liquid chromatography (LC) and capillary electrochromatography (CEC) separations of common anions. The ions were separated using 50 mM phosphate buffer at pH 6.6. Evaluation by LC produced an average of 30,000 theoretical plates (33 cm column length) for the inorganic anions and nucleotides. Evaluation by CEC, using the same buffer, produced enhanced chromatographic performance of up to ca. 90,000 theoretical plates and a theoretical plate height of ca. 4 mum. Although reduced efficiency was observed for inorganic anions that were retained a long time, the results of this study highlight the potential utility of the DMAPAA-Q stationary phase for anion separations.

Preparation and application of organic‐silica hybrid monolithic capillary columns

“…Nevertheless, the preparation process of silica monolithic columns is a bit complicated and it is difficult to control the whole process. Additionally, the post modification is also time consuming since the silica monolithic column usually cannot be used directly 16, 20, 21.…”

Agglomerated carbon based phases for anion exchange chromatography

“…As an alternative to charged surfactants, ionic polymers [20] and ionic latexes [21,22] have been added to silica media to create IC columns. The combination of the silica backbone with latexes yields highly efficient separations, with a quick start-up time and highly reproducible retentions.…”