Electrohydrodynamic Mass Spectrometry: How High Can It Go?

Abstract

In electrohydrodynamic (EH) mass spectrometry (MS) [1], ions are sampled by the action of an electrostatic field applied at the tip of a biased (typically 8 kV) metal capillary containing an ionic solution (Fig. 1). In the absence of bombardment (as in fast atom bombardment or liquid secondary ion MS) or bulk evaporation of solution droplets and concomittant concentration effects (as in electrospray or thermospray MS), EH MS avoids sampling-induced chemical artifacts, making it perhaps the simplest of the desorption ionization (DI) methods relying on solution chemistry for assistance in ionization and/or sampling. However, EH sampling can amplify chemical effects on the efficiency of “matrix assisted” MS. This amplification can offer insight useful in optimizing selectable chemical parameters in the various DI methods. Toward this end, data from a series of experiments was reviewed, assessing factors potentially limiting the mass range of EH MS.