Minimizing analyte electrolysis in electrospray ionization mass spectrometry using a redox buffer coated emitter...

Area of Science:

• Analytical Chemistry
• Electrochemistry
• Materials Science

Background:

• Electrospray ionization mass spectrometry (ESI-MS) is a powerful analytical technique.
• Uncontrolled electrode potentials in ESI-MS can lead to undesirable analyte oxidation.
• Developing methods to control interfacial potential is crucial for accurate ESI-MS analysis.

Purpose of the Study:

• To construct and evaluate an emitter electrode coated with electroactive poly(pyrrole) (PPy) for electrospray ionization mass spectrometry (ESI-MS).
• To investigate the ability of the PPy film to act as a surface-attached redox buffer.
• To assess the impact of the PPy coating on analyte oxidation during ESI-MS.

Main Methods:

• Fabrication of an emitter electrode coated with a poly(pyrrole) (PPy) polymer film.
• Electrospray ionization mass spectrometry (ESI-MS) analysis using both bare metal and PPy-coated electrodes.
• Comparison of analyte (reserpine, amodiaquine) oxidation under different electrode conditions.
• Investigation of the PPy film's redox buffering capacity and its restoration.

Main Results:

• The PPy-coated electrode effectively suppressed the oxidation of analytes (reserpine, amodiaquine) observed with a bare gold electrode.
• A semi-quantitative relationship was established between analyte oxidation rate and emitter interfacial potential.
• Redox buffer capacity correlated with analyte oxidation potential and film charge capacity.
• Online reduction via negative ion mode ESI successfully restored the PPy film's buffering capacity.

Conclusions:

• Poly(pyrrole) coated electrodes serve as effective redox buffers in ESI-MS, mitigating analyte oxidation.
• The PPy film's buffering performance is dependent on analyte properties and film characteristics.
• Restoration of the PPy film's redox buffering capacity is achievable, enabling sustained performance in ESI-MS applications.