Capillary electrochromatography using a fluoropolymer as the chromatographic support material

Fused-silica capillary columns were packed with ethylene chlorotrifluoroeth ylene (ECTFE) particles for use in capillary electrochromatography (CEC). E lectroosmotic flow (EOF) was generated in these columns using acetonitrile- water mixtures as the mobile phase. Electroosmotic mobilities of 1.6 x 10(- 4) cm(2) V-1 V-1 (linear velocities of 1 mm s(-1)) were observed using a mo bile phase without an electrolyte present. The EOF in the ECTFE-packed colu mns is enhanced when using trifluoroacetic acid (TFA) as a mobile phase add itive; electroosmotic mobilities of 3.65 x 10(-4) cm(2) V-1 s(-1) (linear v elocity of 2.5 mm s(-1)) were observed. This enhancement of EOF is attribut ed to dynamic coating of the ECTFE particles by TFA. Other electrolytes (i. e., Tris/Tris-HCl buffer and H3PO4) in the mobile phase did not have such a n enhancement of EOF. However, a slight enhancement of EOF is observed, for example, if small quantities of TFA are added to the mobile phase containi ng Tris buffer. The potential of ECTFE for CEC is demonstrated by separatin g a mixture of amino acids.