Infrared laser-assisted desorption electrospray ionization mass spectrometry

Area of Science:

• Analytical Chemistry
• Mass Spectrometry
• Spectroscopy

Background:

• Direct analysis of complex samples like biological fluids and pharmaceuticals often requires extensive sample preparation.
• Conventional electrospray ionization (ESI) methods can be limited by sample matrix effects and require specific solvent conditions.

Purpose of the Study:

• To develop and demonstrate a novel mass spectrometry technique, Infrared laser-assisted desorption electrospray ionization (IR LADESI), for direct analysis of water-containing samples.
• To evaluate the capability of IR LADESI for analyzing complex biological fluids and pharmaceutical products under ambient conditions.

Main Methods:

• Modification of an ion trap mass spectrometer with a pulsed Er:YAG infrared laser (2.94 microm) coupled via optical fiber for desorption.
• Integration of a nanoelectrospray source for ionization of desorbed material at atmospheric pressure.
• Analysis of analytes in aqueous solution placed on a stainless steel target, irradiated by the laser.

Main Results:

• IR LADESI successfully generated mass spectra for peptide and protein samples comparable to conventional electrospray.
• Direct analysis of untreated blood and urine samples was achieved, demonstrating the method's applicability to complex biological fluids.
• Pharmaceutical products were also analyzed directly, showcasing the versatility of the IR LADESI technique.

Conclusions:

• IR LADESI is a viable method for the direct, ambient analysis of water-containing samples, including complex biological fluids and pharmaceuticals.
• The technique simplifies sample handling and preparation, offering a more efficient approach to mass spectrometry analysis.
• Further investigation into the role of water as a matrix in the IR LADESI process is warranted.