Abstract
Temperature-responsive chromatography using thermoresponsive polymers is innovative and can control analyte retention via column temperature. Analyte elution behavior in this type of chromatography depends on the modified thermoresponsive polymer and the structure of the base materials. In the present study, we examine the effect of the pore diameter of silica beads on analyte elution behavior in temperature-responsive chromatography. Poly(N-isopropylacrylamide-co-n-butyl methacrylate) hydrogel was applied to beads of various pore sizes: 7, 12, and 30 nm. Almost the same amount of copolymer hydrogel was applied to all beads, indicating that the efficiency of copolymer modification was independent of pore size. Analyte retention on prepared beads in a packed column was observed using steroids, benzodiazepines, and barbiturates as analytes. Analyte retention times increased with temperature on packed columns of 12- and 30-nm beads, whereas the column packed with 7-nm beads exhibited decreased retention times with increasing temperature. The difference in analyte elution behavior among the various pore sizes was attributed to analyte diffusion into the bead pores. These results demonstrate that bead pore diameter determines temperature-dependent elution behavior.
Highlights
Temperature-responsive chromatography using thermoresponsive polymers is innovative and can control analyte retention via column temperature
PNIPAAm-modified silica beads are used as the stationary phase, and hydrophobic interaction between PNIPAAm and the analyte is modulated by changing temperature
The morphology of the beads was observed by field emission scanning electron microscopy (FE-SEM) before and after modification by the P(NIPAAm-coBMA) copolymer hydrogel (Supplementary Fig. S1)
Summary
Temperature-responsive chromatography using thermoresponsive polymers is innovative and can control analyte retention via column temperature. We examine the effect of the pore diameter of silica beads on analyte elution behavior in temperature-responsive chromatography. One of them is using thermoresponsive polymer, poly(N-isopropylacrylamide) (PNIPAAm), modified stationary phase for temperature-responsive chromatography[4,5,6,7]. The structure of silica beads, especially pore diameter, is an essential factor in the separation efficiency of a chromatographic stationary phase, this has not been studied in temperature-responsive chromatography. To investigate the effect of pore diameter on analyte elution in temperature-responsive chromatography, stationary phases were prepared using silica beads with various pore diameters (7, 12, and 30 nm) as base materials (Fig. 1). The effect of the pore diameter of the temperature-responsive stationary phase on the elution behavior of the analytes has been investigated
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