Hydrophobic-phase-modified fused-silica columns for capillary electrophoresis

Coated capillaries modified with a hydrophobic layer were developed. Linear hydrocarbons and ethylbenzene modified surfaces greatly improved the elect rophoretic performance of the capillaries. The column efficiency for organi c compounds reached as high as 327 000 theoretical plate numbers per meter on a 50 mu m I.D. linear hydrocarbon (C-6) surface treated fused-silica cap illary column. This value did not change during 50 repeated analyses and th e columns showed strong stability against 0.1 M NaOH and 0.1 M HCl. The rel ative standard deviation of the run-to-run, day-to-day, and capillary-to-ca pillary coating with hydrophobic layer showed Values of less than or equal to 2.5%, and good reproducibility. The separations of four aromatic amines and six pharmacological amines at pH 2.5 is reported. (C) 2000 Elsevier Sci ence B.V. All rights reserved.