The modification of porous chromato‐gel surface for liquid chromatography by poly(4‐vinylpyridine) microgels

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Abstract
A porous chromato‐gel for liquid chromatography was modified by fixing poly(4‐vinylpyridine) (P4VP) microgels of homogeneous size on its surface, and the microgels were further quarternized by using iodomethane or bromoacetic acid, in order to vary the chromatographic characters of the original chromato‐gel. The character of the porous chromato‐gel before and after modification was investigated by the retention volume (Ve) of dextran and pullulan standards with various molecular weights (MW: 2 × 10–2 × 106 g/mol). It was found that a single layer of microgels had been fixed compactly on the surface of the chromato‐gel, and the retention volume (Ve) and the limit exclusion molecular weight (LEMW) [the molecular weight where the d(Ve)/d(MW) became maximum] were affected remarkably by the sizes and chemical characters of the fixed microgels. The retention volume and LEMW decreased when the pore size formed by microgels was smaller than the hole size of the chromato‐gel, while the reverse result was obtained when the pore size formed by the microgels became larger than the hole size of the chromato‐gel. After the microgels were quarternized, the retention volume decreased further. Furthermore, the chromato‐gel quarternized by bromoacetic acid showed excellent chromatographic character. This study provided an advantage in that the chromatographic characters of the chromato‐gel can be varied and improved easily. © 1993 John Wiley & Sons, Inc.