Plasma ionization under simulated ambient Mars conditions for quantification of methane by mass spectrometry

Abstract

Ambient ionization techniques enable ion production in the native sample environment for mass spectrometry, without a need for sample preparation or separation. These techniques provide superior advantages over conventional ionization methods and are well developed and investigated for various analytical applications. However, employing ambient ionization techniques for in situ extra-terrestrial chemical analysis requires these techniques to be designed and developed according to the ambient conditions of extra-terrestrial environments, which substantially differ from the ambient conditions of Earth. Here, we report a plasma ionization source produced under simulated ambient Mars conditions for mass spectrometry. The plasma ionization source was coupled to a quadrupole mass spectrometer, and quantitative and qualitative analyses of trace amounts of methane, as an analyte of interest in Mars discovery missions, were demonstrated. The miniature plasma source was operational at a net power as low as ∼1.7 W in the pressure range of 4-16 Torr. A detection limit as low as ∼0.15 ppm (v/v) at 16 Torr for methane was demonstrated.

Mass spectrometry and planetary exploration: A brief review and future projection

“…When coupled with a commercial laser ablation system, laboratory ICPMS routinely deliver percent‐level accuracy/precision with detection limits at or below picograms per gram (eg, Gonzalez et al), though single particle detection enabled by ICPMS has emerged as an exciting new avenue in nanomaterial research (eg, Lee et al). Investments in the miniaturization of plasma sources (eg, Franzke et al), including plasmas designed for operations at ambient pressures (eg, Tendero et al) and low‐power/self‐sustaining ICP sources adapted for specific planetary environments (eg, Taghioskoui and Zaghloul), suggest that a spaceflight ICPMS will become a reality in the next decade. Such an instrument may be combined with a pulsed laser source, enabling in situ chemical imaging without requiring sample contact (see Section below).…”

A prospective microwave plasma source for in situ spaceflight applications

“…In the commercial realm, plasmas are routinely applied as robust and reproducible sources for optical emission spectra, 5,6 as well as ionized organic compounds and monoatomic ions for mass spectrometry. [7][8][9][10][11][12][13][14] Commercial inductively coupled plasmas (ICPs) operate at high power output (>1 kW) and ionize desolvated solutions or ablated geologic material. Recent advances in plasma technology demonstrate that low power plasma sources, operating at ambient or reduced pressure, perform direct desorption and ionization of molecular compounds or geologic materials in their native state, although the potential to atomize large particles remains poorly constrained.…”