Tandem Mass Spectrometry of Peptide Ions by Microwave Excited Hydrogen and Water Plasmas

Abstract

A thermal cracking cell that served as the atomic hydrogen source for hydrogen attachment/abstraction dissociation (HAD) analysis has an intrinsic problem to produce a beam of atoms reactive against heated tungsten capillary. A plasma excited by 2.45 GHz microwave discharge can deliver reactive species to a quadrupole ion trap confining analyte ions without excessive heating of the radical source components. The radical (H) production performance of the developed source was evaluated by optical emission spectroscopy and H attachment reaction to fullerene ions. The source exhibited the H attachment rate as high as a thermal cracking source forming H in the high temperature tungsten capillary to induce fragmentation processes preserving post-translational modifications. Water vapor was introduced to the source to confirm the stability to generate oxygen containing radicals, which were found present in the water vapor plasma together with atomic hydrogen. Injection of radicals from a water vapor plasma successfully dissociated peptide ions to c-/z- and a-/x-type ions as the case of HAD induced by a thermal cracking cell.

Ion‐molecule reactions of mass‐selected ions

“…IMR can be utilized in combination with other experimental and theoretical techniques. For example, a three‐pronged approach for structure characterization of radical ions of peptides including IMR, IRMPD ion spectroscopy and DFT calculations have been successfully employed by multiple research groups for Cys‐, and Trp‐based and other peptide radicals (Asakawa et al, 2018a, 2018b, 2020a, 2020b, 2019a, 2019b; Asakawa, Takahashi, Sekiya, et al, 2019; Shimabukuro et al, 2018; Takahashi et al, 2016, 2018). A similar, three‐pronged investigation that we did not discuss in this review was conducted by the Fornarini group.…”

“…Similarly, IMR play an important role in structure identification of radical ions of peptides (Lanucara et al, 2014;Piatkivskyi, Piatkivskyi, Hurt, et al, 2014;Piatkivskyi, Piatkivskyi, Ryzhov, et al, 2014), especially since ion dissociation methods are often hampered by the facile radical rearrangement. Lastly, a novel radical-based dissociation method, HAD has been recently developed by Takahashi and coworkers (Asakawa et al, 2018a(Asakawa et al, , 2018bAsakawa et al, 2020aAsakawa et al, , 2020bAsakawa et al, 2019aAsakawa et al, , 2019bAsakawa et al, 2019;Shimabukuro et al, 2018;Takahashi et al, 2016;Takahashi et al, 2018). While formally it is not an ion-molecule but rather an ion-atom process, we have reviewed its recent advances as part of mass-selected ion/neutral interactions.…”

“…More recently, the authors used an alternative way of producing neutral radical species for the reactions with analyte ions. Instead of heating hydrogen gas over W, they interfaced a microwave-driven capacitively coupled plasma generator to the ion trap (Shimabukuro et al, 2018). Different gases can be excited by this plasma-hydrogen gas still produces H atoms, oxygen yields 3 O atoms, while water vapors plasma-H•, 3 O•, and •OH radicals.…”

Identifying Double Bond Positions in Phospholipids Using Liquid Chromatography-Triple Quadrupole Tandem Mass Spectrometry Based on Oxygen Attachment Dissociation

“…7) As reported by Shimabukuro and co-workers, the microwave-driven ICP source generates a higher radical ux than the microwave-driven CCP source at a high vacuum (< 0.1 Pa). 10,11) Since the gas pressure of the collision cell is equivalent to the operating pressure of the microwave-driven ICP (≈ 0.1 Pa), the latter can be directly connected to the collision cell without the need for di erential pumping.…”

Microwave excitation of a low-energy atomic hydrogen

“…Besides these spatial problems, the RF plasma requires power input and gas input higher than the microwave plasma. We have been developing two types of neutral beam sources utilizing microwave discharge: the capacitively coupled plasma (CCP) type with a needle shaped electrode [11], and the localized inductively coupled plasma (LICP) type that couples the input microwave power to the plasma by winding a coil around a small diameter dielectric tube [12]. In this report, improvements of the LICP neutral beam source and the comparison in performance with the old sources are described.…”