A sample preparation method for recovering suppressed analyte ions in MALDI TOF MS

Area of Science:

• Analytical Chemistry
• Mass Spectrometry
• Biochemistry

Background:

• Analyte suppression effects (ASE) in matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF MS) hinder the detection of target compounds in complex samples.
• Conventional dried-droplet sample preparation methods can lead to analyte embedding within matrix crystals, exacerbating ASE.

Purpose of the Study:

• To develop and validate a modified thin-layer sample preparation method for MALDI TOF MS.
• To significantly reduce the analyte suppression effect (ASE) in the analysis of multicomponent mixtures.

Main Methods:

• A modified thin-layer sample preparation technique was employed, where analytes were deposited on top of preloaded matrix on the MALDI plate.
• Sample solutions were prepared without matrix, and efforts were made to avoid re-dissolving the preloaded matrix to prevent analyte embedding.
• Model mixtures of peptides, synthetic polymers, and lipids were analyzed using both the conventional dried-droplet method and the modified method.

Main Results:

• The modified thin-layer method significantly reduced analyte suppression effects compared to the conventional dried-droplet method.
• Analyte ions that were completely suppressed using the conventional method were effectively recovered with the modified technique.
• Detection of analytes in model mixtures of peptides, polymers, and lipids showed marked improvement.

Conclusions:

• Analyte incorporation within matrix crystals is a significant contributor to analyte suppression effects in MALDI TOF MS.
• The developed modified thin-layer sample preparation method effectively mitigates ASE.
• This method offers a valuable tool for direct MALDI MS analysis of complex, multicomponent mixtures.