Multi-particle frits for packed capillary columns in electrochromatographic use

摘要

Further development of capillary electrochromatography (CEC) is to some extent restricted by column technology. Packed capillary columns are most commonly used in CEC because of higher sample capacity and higher sensitivity than open tubular columns, and better reproducibility and uniformity than monolithic columns. Fritting is the core component for the fabrication of packed capillary columns. Therefore various fritting technologies attract continuous attention from analytical community. A convenient fritting method was developed in this study. In contrast to the reported single-particle fritting, this method applies a multi-particle fritting technology to hold stationary phase in capillary columns. Several large porous particles smaller than the column internal diameter were tapped in and immobilized in inlet and outlet of the packing material bed due to direct and indirect keystone effect. Except the smallest permeability by the sintered frit and the lowest breaking pressure by the single-particle frit, EOF mobility and peak dispersion of the multi-particle frit were at the same levels with the formers. In addition, all the three frits avoided bubble formation. It demonstrated that the multi-particle frits met the general requirements of permeability, mechanical resistance and efficiency for packing capillary microcolumns as well as the sintered frits and the single-particle frits. Thus, peak efficiency around 4.3 mu m, plate height (approximately 232,560 plates per meter) was obtained by multi-particle fritted capillary columns with electrokinetic packing, compared to 6.5 mu m plate height by single-particle fritted columns with slurry pressure packing. In particular, the multi-particle fritting was simpler, faster, and more reproducible than the sintered fritting, and the multi-particle fritting was suitable to pack capillary columns of various capillary bore sizes owing to rich commercial resources of fritting particles of various diameters. Multi-particle fri