Over the last 5 years, this laboratory has developed the liquid sampling-atmospheric pressure glow discharge (LS-APGD) microplasma as an ionization source, initially for atomic mass spectrometry applications. Different from the ICP, the microplasma is directly coupled to mass spectrometers designed to sample electrospray ionization (ESI) sources; i.e. the vast majority of LC-MS instruments. In fact, the source has been coupled to single and triple quadrupoles, ion traps, and Orbitrap instruments. While not as sensitive as the ICP (yet), isotope ratio performance on par with the state-of-the-art sector instruments has been achieved on an Orbitrap platform. To complement the ability to perform elemental analysis, the microplasma can be operated using solvent systems commonly employed in LC-MS, producing “molecular” mass spectra that are essentially equivalent to those of APCI. Test compounds have ranged from small molecules (caffeine) to metalloproteins where the mass spectra are multi-charged intact molecules including metal constituents. In this way, the LS-APGD represents a practical Combined Atomic and Molecular (CAM) ionization source. In this presentation, we will lay out the basic operation principles and attributes of the microplasma and how it provides high information density as a CAM device.

Liquid sampling-atmospheric pressure glow discharge (LS-APGD) microplasma: A combined atomic and molecular (CAM) ionization source

255th National Meeting (2018)

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