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Variable Mixing with Theta Emitter Mass Spectrometry: Changing Solution Flow Rates with Emitter Position
Casey J Chen1, Evan R Williams1
1Department of Chemistry, University of California, Berkeley, California 94720, United States.
Analytical Chemistry
|September 20, 2023
Summary
Carefully positioning theta glass emitters is crucial for controlling solution mixing and droplet composition in mass spectrometry. Precise emitter placement ensures accurate measurements of reaction kinetics and reagent concentrations.
Area of Science:
- Analytical Chemistry
- Physical Chemistry
Background:
- Theta glass emitters enable rapid mixing of solutions for analysis.
- Controlling relative flow rates is essential for reproducible results in electrospray ionization mass spectrometry (ESI-MS).
Purpose of the Study:
- To investigate the impact of theta glass emitter positioning on solution mixing and droplet composition.
- To demonstrate a method for controlling reagent concentrations and studying reaction kinetics.
Main Methods:
- Utilizing theta glass emitters for rapid solution mixing.
- Employing electrospray ionization mass spectrometry (ESI-MS) for product analysis.
- Systematically varying emitter tip position relative to the mass spectrometer inlet.
Main Results:
- Emitter position significantly alters relative flow rates, with variations up to three orders of magnitude.
- Protein charge state (myoglobin) changed from +7.8 to +13.8 with varying sulfolane concentration.
- Bimolecular reaction conversion ratios shifted from 0.98 to 0.04 based on emitter position.
Conclusions:
- Droplet composition is highly sensitive to theta glass emitter position.
- Precise control of emitter placement is necessary for accurate kinetic studies and reproducible ESI-MS experiments.
- This method allows for the study of reaction kinetics across a range of solution concentrations using a single emitter setup.
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