Electrophoresis-By-Accident in Electrospray Ion Source

Area of Science:

• Analytical Chemistry
• Separation Science
• Mass Spectrometry

Background:

• Sample preparation for mass spectrometry (MS) is often complex and time-consuming.
• Existing hyphenated separation techniques are effective but expensive and require significant user attention.
• There is a need for simpler, more cost-effective methods for analyzing complex samples with MS.

Purpose of the Study:

• To develop a facile, low-cost online MS method for analyzing complex samples.
• To enhance analyte signals in MS analysis without complex instrumentation.
• To demonstrate the broad applicability of the developed method for various analytes and matrices.

Main Methods:

• Utilized a standard unmodified electrospray ionization (ESI) source with polyether ether ketone tubing.
• Implemented a run-stop-run sequence where sample flow was stopped to allow electric-field-induced microseparation of ionic species.
• Restarted the flow to introduce separated species into the mass spectrometer for analysis.

Main Results:

• Achieved significant enhancement of analyte signals compared to direct infusion, with signal change factors ranging from 0.74 to 295.
• Demonstrated that the signal enhancement is due to microseparation of analyte and matrix ions within the sample flow line.
• Confirmed the intrinsic property of ESI operated in a run-stop-run sequence for improved MS analysis.

Conclusions:

• The developed online ESI-MS method is a simple, low-cost approach for complex sample analysis.
• This technique offers broad applicability for analyzing metabolites, peptides, and proteins in various complex matrices.
• The fundamental finding has the potential for widespread adoption given the large number of existing ESI-MS systems worldwide.