Vacuum Matrix-Assisted Ionization Source Offering Simplicity, Sensitivity, and Exceptional Robustness in Mass...

Area of Science:

• Analytical Chemistry
• Mass Spectrometry

Background:

• Traditional mass spectrometry ionization methods often require external energy sources like lasers or high voltages.
• Vacuum matrix-assisted ionization (vMAI) offers an alternative by utilizing matrix compounds that spontaneously ionize analytes in a vacuum.
• Existing vMAI approaches may have limitations in sample introduction speed and throughput.

Purpose of the Study:

• To develop and characterize a novel vacuum matrix-assisted ionization (vMAI) source for a Thermo Orbitrap mass spectrometer.
• To demonstrate the rapid sample introduction and ionization capabilities of the new vMAI source.
• To assess the performance of the vMAI source in terms of sensitivity, carryover, and applicability to complex samples.

Main Methods:

• A custom vMAI source was constructed and integrated into a Thermo Orbitrap mass spectrometer, replacing the commercial inlet.
• Matrix/analyte samples were introduced via a probe into the "S-lens" entrance region for direct ionization.
• Ion transmission was facilitated by a low voltage, with airflow used for modulation.
• The performance was evaluated using erythromycin as an analyte and 3-nitrobenzonitrile as a matrix, with subsequent testing on biological fluids, bacterial extracts, and tissue samples.

Main Results:

• The vMAI source enabled rapid sample introduction and ionization without external energy input (laser, heat, high voltage).
• Picogram levels of erythromycin produced stable mass spectra for over a minute, with the MH+ ion as the base peak.
• Minimal carryover was observed, even with high concentration samples and complex mixtures, when the probe was cleaned between acquisitions.
• Analyses of diverse biological samples showed no instrument contamination, and typical ultrahigh resolution and mass accuracy were maintained.

Conclusions:

• The developed vMAI source provides a simple, robust, and efficient method for mass spectrometry analysis.
• This approach facilitates rapid sample introduction and sensitive ionization, suitable for complex matrices and potentially high-throughput applications.
• The technology holds promise for enhancing the robustness and applicability of various mass spectrometers.