Determination of isoflavones using capillary electrophoresis in combination with electrospray mass spectrometry

Abstract

Various isoflavones were separated on an uncoated fused-silica capillary electrophoresis (CE) column (110 cm × 75 μm I.D.) using 25 m M ammonium acetate buffer and UV and electrospray ionization mass spectrometric (ESI-MS) detection. CE-ESI-MS with negative-ion electrospray ionization has been shown to be a suitable technique for the determination of this type of natural compound. The modest sample loading of the CE technique can be circumvented by coupling it with MS; in addition, the mass-resolving capability and high sensitivity of MS for structural analysis of mixtures can thus be exploited. Furthermore, ESI-MS allows one not only to determine the molecular mass of isoflavones, but also the presence of various functional groups according to observed losses from the [M - H] − ion during collision-induced dissociation by adjusting some MS parameters.