The relationship between polymer structures on silica particles and the separation characteristics of the corresponding columns for hydrophilic interaction chromatography

Silica particles with various pore sizes were modified with poly(acrylamide) via surface-initiated atom-transfer radical polymerization (SI-ATRP) under different reaction conditions. Twenty different columns were prepared and characterized according to a test method for hydrophilic interaction chromatography (HILIC) columns. Hydrophilic retention by the SI-ATRP columns was much higher than that of poly(acrylamide) columns prepared via free-radical polymerization and many commercially available HILIC columns. The SI-ATRP columns displayed greater selectivity for -OH groups than any of the HILIC columns based on their alpha(U/2dU) values. SI-ATRP functionalization was used to increase the polymer chain density on the silica particles, which suggested a brush-type morphology, and improved hydrophilic selectivity. This indicated that hydrophilic retention and selectivity could be controlled by adjusting the morphology of the organic stationary phase. This stationary phase design strategy was validated experimentally by the effective separation of highly hydrophilic analytes. The findings of this study will greatly contribute to the creation of better separation media. (C) 2020 Elsevier B.V. All rights reserved.