On-line micellar electrokinetic chromatography mass spectrometry with a high-molecular-mass surfactant

On-line coupling of micellar electrokinetic chromatography and electrospray ionization mass spectrometry (MEKC-ESI-MS) using a high-molecular-mass surfactant was explored. Some standard mixtures, pharmaceuticals and industrial surfactants were separated and detected with 1% butyl acrylate-butyl methacrylate-methacrylic acid copolymer sodium salt (BBMA) in 20 mM ammonium formate !(pH 7). The effect of the concentration of surfactants on sensitivity was studied with direct injection of caffeine to the ESI-MS. The partial filling technique in MEKC was studied with BBMA. Before the pseudo-stationary phase zone reached the detector, six non-ionic naphthalene derivatives were separated successfully by partial filling MEKC with a 5% BBMA zone introduced at 50 mbar for 20 s. The partial filling method was also applied to the on-line MS detection of caffeine and its metabolites. (C) 1998 Elsevier Science B.V.