Preparation of uniformly sized polymeric separation media potentially suitable for small-scale high-performance liquid chromatography and/or capillary electrochromatography

Uniformly sized polymer particles were prepared by either a two-step swelling and polymerization method or a Shirasu porous glass (SPG) emulsification technique to compare their suitability as a uniformly sized packing material for small-scale high-performance liquid chromatography (HPLC) or capillary electrochromatography (CEC). The SPG emulsification technique afforded slightly worse size uniformity compared to the two-step swelling and polymerization technique. However, fairly nice spherical shapes with reproducible outward appearance and internal pore size distribution were obtained for both of 3- or 6-mu m sized particles. On the other hand, the two-step swelling and polymerization method afforded broken particles with quite different outward appearances due to the polymeric porogen effects of seed polymer utilized as the shape template. In HPLC, the column packed with the 3-mu m particles prepared with the SPG emulsification technique proved to have a fairly high column efficiency with good column stability, as assessed under repeated use in gradient elution. On the other hand, the column packed with the packing material obtained through the two-step swelling and polymerization method showed much poorer column stability, while initial column efficiency was compatible to that obtained using the SPG emulsification method. In addition, the packing material prepared with the SPG emulsification technique could be modified with ion-exchangeable monomers and showed fairly good column efficiency in the CEC mode. (C) 1999 Elsevier Science B.V. All rights reserved.