ELECTROSPRAY ION SPRAY - A COMPARISON OF MECHANISMS AND PERFORMANCE

Aspects of the major processes in electrospray (ES) were examined on the basis of total ES current and mass-analyzed ion current measurements, which were performed with a triple-quadrupole mass spectrometer equipped with an atmospheric pressure source. The dependence of these currents on the presence of electrolyte in the solution indicated that the charging of the droplets is electrophoretic. The droplets are charged due to an excess of electrolyte ions of the same polarity. The equation for the capillary potential leading to ES onset due to D. P. H. Smith was found to be valid for methanol, acetonitrile, and water solvents. The dependence of the currents on electrolyte concentration, capillary potential, solution flow rate, and solvent for electrospray and ion spray (IS) was examined. IS was found to maintain its performance over a somewhat wider range of changes in the above parameters.