Adjacent pulsed nanoelectrospray ionization emitters for the alternating generation of ions of opposite polarity.

An approach that allows for adjacent closely spaced nanoelectrospray ionization (nESI) emitters to be pulsed alternately to generate ions of opposite polarity for transmission through a common interface is described. The potential difference between two or more nESI emitters in close proximity is minimized by applying the same polarity to both emitters at any given point in time but with the magnitude of only the active emitter's potential being sufficiently high to sustain a stable spray. The reduced difference in potential between emitters allows the distance between emitters to be decreased to within a few millimeters so that compromises imposed by the use of multiple emitters for the generation of ions from distinct solutions using a common atmosphere interface are minimized.