A multi-electrode glow discharge ionization source for atomic and molecular mass spectrometry

A new, multi-electrode, liquid sampling glow discharge ionization source for mass spectrometry is described. This ion source consists of multiple (2-4) counter (anode) electrodes in comparison to prior single counter electrode designs of this type. In the experiments presented here these ion sources have been interfaced with ThermoScientific Exactive Orbitrap instruments and Advion Expression Compact Mass Spectrometer instruments. Advantages and analytical performance improvements are described. These include the ability to use higher plasma currents, resulting in a more robust and energetic plasma exhibiting higher sensitivity, lower spectral background, ppt detection limits, and 2-3x faster washout times. A low-cost, 3D printed version of a dual counter electrode design is also described. The ion source can further be utilized in either atomic (elemental/isotopic) or molecular (molecular ion, fragmentation) ionization modes.