The Developement of a Hydrodynamic Flow Assisted Double Junction Interface for Sensitivity Improvement of Sulfonamides Analysis in MEKC-ESI/MS

A hydrodynamic flow assisted double junction interface was developed by the combination of hydrodynamic flow and electric field to alleviate ion suppression caused by nonvolatile surfactants in micelle electrokinetic chromatography electrospray ionization mass spectrometry. In this interface, the conventional fused silica transfer column was replaced with a polyvinyl alcohol coated (PVA) column. With minimal EOF, the velocity of an ion was determined by its electrophoretic velocity and the hydrodynamic flow applied to the interface. During the analysis, hydrodynamic flow was adjusted to allow only analytes flowing into the ESI source. On the other hand, the ADS of higher electrophoretic mobility was controlled by the electric field to be retained in the junction reservoir. In this way, the problem of signal suppression caused by negative charged salt ADS could be successfully solved, and thus the S/N ratio would be increased significantly.