Combined Atomic and Molecular (CAM) Ionization: The Diversity of the Liquid Sampling – Atmospheric Pressure Glow Discharge (LS-APGD) on a Compact Mass Spectrometer

Mass spectrometric techniques are typically divided into two distinct fields: atomic and molecular. Liquid sampling – atmospheric pressure glow discharge (LS-APGD) has been developed as a versatile ionization source capable of combined atomic and molecular (CAM) analysis. To date, the LS-APGD has demonstrated impressive results in U isotope ratio analysis as well as molecular analysis across a wide range of instrument platforms.1-3 While molecular sampling has been demonstrated on this source, these samples fall into the realm of ESI-type samples, larger, polar compounds, most commonly LC-relevant drug targets. Presented here will be the demonstration of the wider versatility of the LS-APGD as a CAM ionization source using the Advion expression Compact Mass Spectrometer (CMS).

Authors: Tyler Williams1, Jacob R. Bills1, Jamey Jones2, and R. Kenneth Marcus1
1Clemson University, Department of Chemistry, Clemson, SC 29634
2Advion Inc, Ithaca, NY 14850

This poster was presented at the ASMS 2020 Reboot.

Coupling the Liquid Sampling – Atmospheric Pressure Glow Discharge, A Combined Atomic and Molecular (CAM) Ionization Source, To a Reduced-Format Mass Spectrometer for the Analysis of Diverse Species

Clemson University


The LS-APGD microplasma has shown potential as a combined atomic and molecular (CAM) ionization source, though to this point it has been solely interfaced with large, laboratory-scale instruments. There are many instances wherein reduced-format, lower operating overhead, analyzers are appropriate. To this end, the LS-APGD has been coupled with an Advion expressionL Compact Mass Spectrometry (CMS) for the analysis of diverse samples. This instrument has been previously travel hardened in accordance to MIL-SPEC-810, demonstrating its suitability for in-field analysis. The coupling of the LS-APGD to this instrument expands its capability for diverse analyses, with early-stage figures of merit presented here. With this new coupling, a thorough optimization of both the instrument ion optics and the LS-APGD operating parameters was necessary as this platform does not have a direct method for collisional dissociation of potentially-deleterious molecular species. Under the optimized conditions, analytical response curves were constructed for Na, Rb, Cs, and Tl, demonstrating detection limits between 17.6–146 ng mL−1 (single ng, absolute). Furthermore, CAM sampling capabilities can be realized upon changing from a 2% HNO3 to a 70 : 30 MeOH : H2O solvent system, providing molecular-level chemical information readily obtained from atomic ionization sources such as the inductively coupled plasma (ICP-MS). Here detection limits between 1–32 nM (single pg, absolute) were obtained for caffeine, acetaminophen, Δ9-tetrahydrocannabidiol, sulfadimethoxine, terfenadine, and reserpine. The unique features of the CAM ionization source on this flexible MS platform hold promise for many operation environments.