On-line coupling of partial-filling micellar electrokinetic chromatography with mass spectrometry

The on-line coupling of micellar electrokinetic chromatography (MEKC) with mass spectrometry (MS) is hampered by the presence of high concentrations of surfactant in the electrolyte system. Partial-filling MEKC (PF-MEKC) provides a possible way to overcome this problem. In PF-MEKC only a part of the capillary is filled with an electrolyte solution containing micelles, thus allowing an MEKC separation without allowing surfactant to enter the mass spectrometer. The migration behaviour of the micellar zone was investigated applying indirect UV detection. It was demonstrated that micelles gradually break down under PF-MEKC conditions and migrate as surfactant monomers at a concentration at or below the critical micelle possibilities as well as the limitations of PF-MEKC are discussed. On-line PF-MEKC-MS with sodium dodecyl sulphate micelles is demonstrated for some pharmaceuticals applying an atmospheric pressure chemical ionisation interface (C) 1998 Elsevier Science BV