Chiral electrokinetic chromatography-electrospray ionization-mass spectrometry using a double junction interface for both low concentration and high concentration sulfated beta-cyclodextrin

摘要

The utility of using a double junction interface for coupling S-beta-CD EKC with ESI-MS was demonstrated by chiral analysis of DOPA and MDOPA under both counter-migration mode and carrier mode. Under counter-migration mode, S-beta-CD was continuously supplied from junction reservoir to the separation column. As a result, the effective separation length was preserved and chiral separation could still be achieved for DOPA after ten analyses. High concentration of S-beta-CD (carrier mode) was needed for chiral separation of MDOPA. Under acidic conditions using normal polarity across the connecting column, S-beta-CD and phosphate anions have a net mobility towards the junction reservoir, not the ESI source. With this arrangement, ion suppression from S-beta-CD and phosphate ions can be alleviated.