Semipreparative capillary electrochromatography

Capillaries with inner diameters of 550 mum have successfully been packed w ith 1.5-mum octadecyl silica particles using frits made of macroporous poly mers by the UV photopolymerization of a solution of glycidyl methacrylate s ad trimethylolpropane trimethacrylate. This type of frit is found superior to one made of low-melting point poly(styrene-co-divinylbenzene) beads. Bub ble formation is not observed to occur within these capillary columns under our experimental conditions. Separations can be achieved with sample injec tion volumes as high as 1 muL. To demonstrate its semipreparative use, a mi xture of 500 nL of taxol (20 mM) and its precursor, baccatin III (30 mM), i s separated using such a column with a Tris buffer.