Continuous flow infrared matrix-assisted laser desorption electrospray ionization mass spectrometry

Area of Science:

• Analytical Chemistry
• Mass Spectrometry
• Spectroscopy

Background:

• On-line analysis of liquid samples is crucial for monitoring dynamic chemical and biochemical processes.
• Traditional methods may require sample pre-treatment or are not suitable for real-time monitoring.
• Matrix-assisted laser desorption electrospray ionization (MALDESI) offers a sensitive ionization technique.

Purpose of the Study:

• To demonstrate continuous flow infrared matrix-assisted laser desorption electrospray ionization (CF IR MALDESI) for on-line liquid sample analysis.
• To evaluate the capability of CF IR MALDESI for monitoring various chemical and biochemical reactions.
• To establish a novel approach for real-time mass spectrometry analysis of liquid samples.

Main Methods:

• Liquid samples were flowed through a fused-silica capillary (50 µm i.d.) at 1-6 µL/min.
• A pulsed infrared optical parametric oscillator (OPO) laser (2.94 µm, 20 Hz) desorbed and ablated sample from the capillary tip.
• Ejected sample plumes were entrained in an electrospray for ionization by MALDESI and analyzed by mass spectrometry.

Main Results:

• Continuous flow was successfully coupled with IR MALDESI for on-line mass spectrometry.
• The method enabled real-time monitoring of complex reactions, including metal chelation, protein denaturation, and enzymatic digestion.
• High sensitivity and efficiency were demonstrated for analyzing aqueous solutions.

Conclusions:

• CF IR MALDESI is a powerful technique for the on-line analysis of liquid samples.
• This method provides a versatile platform for real-time monitoring of chemical and biochemical processes.
• The developed system offers significant advantages for reaction kinetics studies and process monitoring.