Journal of The American Society for Mass Spectrometry

, Volume 30, Issue 9, pp 1742–1749 | Cite as

Microdroplet Fusion Chemistry for Charge State Reduction of Synthetic Polymers via Bipolar Dual Spray with Anionic Reagents

  • John R. StutzmanEmail author
  • Ryan M. Bain
  • Sebastian Hagenhoff
  • William H. Woodward
  • John P. O’Brien
  • Michael Lesniak
Research Article


Microdroplet fusion chemistry is an emerging area of analyte manipulation that utilizes the ion source region of a mass spectrometer to covalently derivatize or manipulate the charge state distribution. This technique utilizes two electrospray emitters in close proximity, where the droplets from each electrospray plume fuse and undergo the subsequent chemistry. In this study, microdroplet fusion chemistry via bipolar dual spray has demonstrated the ability to reduce the average charge state of polyethylene glycol (PEG) cations using anionic reagents. Bipolar dual spray was implemented on a commercial mass spectrometer with limited hardware modifications to the ion source. Reagents including ammonium hydroxide, formic acid, and lithium chloride showed dramatic shifts in the average charge state of PEG 3.8 K cations (e.g., 5.0+ to 2.5+) along with the emergence of newly detected charge states. An organic base, tributylamine, had no effect on the charge state distribution of PEG 3.8 K cations. These results were consistent with an ion-pairing mechanism, where reagent anions destabilized ammonium cation interactions with PEG 3.8 K upon droplet fusion from the negative and positive emitters. Additional bipolar dual spray experiments with PEG 12.6 K demonstrated the ability to transform uninterpretable mass information into distinct charge states ranging from [M+8NH4]+ to [M+3NH4]+. Overall, this study provides insight into the nature of dual spray chemistry and will aid future experimental design in microdroplet covalent chemistry.


Charge reduction Microdroplet fusion chemistry Dual spray Droplet chemistry Synthetic polymers 

Supplementary material

13361_2019_2236_MOESM1_ESM.docx (72 kb)
ESM 1 (DOCX 71 kb)


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Copyright information

© American Society for Mass Spectrometry 2019

Authors and Affiliations

  1. 1.Analytical SciencesThe Dow Chemical CompanyMidlandUSA
  2. 2.Analytical SciencesDow Deutschland Anlagengesellschaft mbHStadeGermany
  3. 3.Plastics CharacterizationThe Dow Chemical CompanyLake JacksonUSA

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