Recently, solution-electrode glow discharges (SEGDs) have shown great utility as ionization sources for mass spectrometry (MS). The solution composition of SEGD electrodes is pivotal to their performance as it influences analyte-ion formation. The performance of electrospray ionization is heavily dictated by spray-solution composition, which can alter ionization efficiency and pathways. While SEGDs produce Taylor cones similar to electrospray ionization, the influence of solution-electrode composition on molecular-ion formation has not been studied. Here, we examine how additives to an atmospheric-pressure solution-cathode glow discharge (SCGD) influence molecular ionization and fragmentation. The impact of several additives to the acidic solution of an SCGD ionization source was evaluated based on mass-spectrometric performance. Addition of methanol increased molecular- and fragment-ion signals for peptide angiotensin II. This effect is likely due to improved desolvation and a greater interaction of analyte molecules with glow-discharge species. Several high-boiling-point reagents were tested to examine changes in the ion signal, the average charge state, and the degree of fragmentation. Overall, these additives inhibited fragmentation but significantly lowered intact molecular-ion signals. Interestingly, loss of fragment ions trended with the boiling point of the reagent used. We hypothesize that analyte molecules become trapped in droplets produced at the solution-cathode surface. These droplets do not fully desolvate before escaping the discharge region, sparing analyte molecules from fragmentation. For low volatility additives, droplets do not desolvate, even as they enter the heated MS, which yields a loss in molecular ions. The changing composition of the SCGD solution alters analytical performance, but also provides insight into analyte ionization and fragmentation processes.
Skip Nav Destination
Article navigation
28 July 2021
Research Article|
July 27 2021
Effects of solvent composition on ionization and fragmentation within the solution-cathode glow discharge
Special Collection:
Plasma-Liquid Interactions
Courtney L. Walton
;
Courtney L. Walton
a)
1
Department of Chemistry and Chemical Biology, Rensselaer Polytechnic Institute
, Troy, New York 12180, USA
Search for other works by this author on:
Andrew J. Schwartz
;
Andrew J. Schwartz
b)
2
Department of Chemistry, University at Buffalo
, Buffalo, New York 14260, USA
Search for other works by this author on:
Jacob T. Shelley
Jacob T. Shelley
c)
1
Department of Chemistry and Chemical Biology, Rensselaer Polytechnic Institute
, Troy, New York 12180, USA
c)Author to whom correspondence should be addressed: shellj@rpi.edu
Search for other works by this author on:
a)
Current address: Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
b)
Current address: Bristol-Meyers Summit, New Jersey 07901, USA.
c)Author to whom correspondence should be addressed: shellj@rpi.edu
Note: This paper is part of the Special Topic on Plasma-Liquid Interactions.
J. Appl. Phys. 130, 043305 (2021)
Article history
Received:
January 16 2021
Accepted:
July 03 2021
Citation
Courtney L. Walton, Andrew J. Schwartz, Jacob T. Shelley; Effects of solvent composition on ionization and fragmentation within the solution-cathode glow discharge. J. Appl. Phys. 28 July 2021; 130 (4): 043305. https://doi.org/10.1063/5.0044454
Download citation file:
Sign in
Don't already have an account? Register
Sign In
You could not be signed in. Please check your credentials and make sure you have an active account and try again.
Sign in via your Institution
Sign in via your InstitutionPay-Per-View Access
$40.00