Doped Argon Surface Desorption Dielectric-Barrier Discharge Ionization Mass Spectrometry for Fragile Compounds

Abstract

Argon surface desorption dielectric-barrier discharge ionization (Ar-SDDBDI) in conjunction with dopants was reported for rapid and sensitive determining of fragile compounds. In dopant/Ar-SDDBDI, analytes are ionized primarily through proton transfer with dopant ions, which are formed in Ar plasma. Different from He, dopant/Ar-SDDBDI generates low energetic ions, and therefore, fragmentation is suppressed. It thus significantly simplifies the mass spectra and the assignment of one peak. Dopants ranging from organic solvents to gaseous materials were systematically studied. The application of dopant/Ar-SDDBDI was demonstrated by analysis of multiple compounds, including antibiotics, amino acids, fatty acids, hormones, pharmaceuticals, and peptides. Rapid profiling of chemicals in such complex matrixes including mixtures and drug tablets was also tested. Positive and negative mass spectra with little to no fragmentation for compounds in the pure state and as mixtures were readily achieved. Limits of detection (S/N = 3) were determined to be 0.60 and 0.36 pmol, respectively, for the analysis of l-alanine and metronidazole. Furthermore, the demonstration applications also included imaging of an "H" character under ambient conditions. These results indicate that the technique by combining of Ar-SDDBDI with dopants exhibits high sensitivity, high spatial resolution, and a very low degree of fragmentation, which render it a potential tool for fragile compound analysis in mass spectrometry imaging.

Plasma‐based ambient mass spectrometry: Recent progress and applications

“…Using SDDBDI for the MSI experiment, the spatial resolution of an imprinted cyclophosphamide T character image was approximately 22 μm. Subsequently, they combined dopants, such as methanol, ethanol, acetone, NH 3 , and so on, with Ar‐SDDBDI to analyze the liable compounds and reduce the fragmentation (Zhang et al, 2018), for which the analytes were ionized primarily through proton transfer with dopant ions. Recently, a study introduced a nanosecond high voltage pulses in DBDI‐MS instead of the conventional microsecond pulses (Ahmed et al, 2020).…”

Pressure-Driven Switching of Photoelectron Impact Ionization-Chemical Ionization/Penning Ionization in Vacuum Ultraviolet Photoionization Mass Spectrometry

“…31 Both ions and metastable atoms/molecules were involved in the ionization process. For example, metastable states of He and Ar played a role in He/Ar-DBDI 28,32,33 and DART. 27,34 A variety of excited states of N 2 molecules participated in the case of N 2 , 35,36 which was confirmed by optical emission spectroscopy.…”