FRITLESS PACKED-COLUMNS FOR CAPILLARY ELECTROCHROMATOGRAPHY - SEPARATION OF UNCHARGED COMPOUNDS ON HYDROPHOBIC HYDROGELS

A novel column is described that does not require frits to keep packin g material within a capillary, A continuous bed is prepared in situ in aqueous solution by radical copolymerization of N-isopropylacrylamide and 2-acrylamido-2-methylpropanesulfonic acid (the resultant gel is d enoted poly(AMPS-co-IPAAm). N,N'-Methylenebisacrylamide is used for cr oss-linking, On the application of an electrical field, electroosmotic now (EOF) is developed in the bed along the capillary, where fluid pr opulsion would be otherwise difficult to achieve, The resultant EOF tr ansports neutral compounds through the column without forcing the gel out of the capillary, Examination of the fluid motion in the continuou s bed using a video microscope system and an image processor shows a r elatively nat now profile of EOF. The bed functions as the stationary phase for reversed-phase capillary electrochromatography (CEC), This n ew approach is an alternative to packed capillary columns which have b een used previously in CEC, A high efficiency is obtained for a steroi d which is separated on a 4.0% total monomer concentration (T), 10.0% degree of cross-linking (C), and 10.0% mole fraction of AMPS in the to tal monomer (S), poly(AMPS-co-IPAAm) column. A mixture of polyaromatic hydrocarbons is separated on a 6.9% T, 5.8% C, and 5.5% S poly(AMPS-c o-IPAAm) column. The capacity factor of benzo[a]pyrene increases from 0.63 to 1.91 as the acetonitrile content in a Tris-boric acid buffer i s decreased from 45 to 30% (v/v), The run-to-run RSD of analyte migrat ion time is less than 0.73%, and the day-to-day RSD is acceptable, Pot ential benefits of this approach are also mentioned.