Optimization of a hydrophobic solid-phase extraction interface for matrix-assisted laser desorption/ionization

Area of Science:

• Analytical Chemistry
• Biochemistry
• Surface Science

Background:

• Matrix-assisted laser desorption/ionization (MALDI) is a key technique for analyzing biopolymers.
• Solid-phase extraction (SPE) is often used for sample preparation in MALDI analysis.
• Hydrophobic surfaces can be utilized for SPE to isolate and desalt analytes.

Purpose of the Study:

• To investigate the use of octadecanethiol (C18)-derivatized MALDI probe surfaces as hydrophobic SPE devices.
• To determine the binding capacity and surface density of peptides on C18-modified probes.
• To assess the influence of analyte concentration and immersion time on peptide binding.

Main Methods:

• Derivatization of MALDI probe surfaces with octadecanethiol (C18).
• Utilizing C18-derivatized probes as hydrophobic SPE devices for biopolymer isolation and desalting.
• Employing quantitative MALDI to measure peptide binding and calculate surface density.
• Varying analyte (peptide) concentrations and immersion times during probe exposure.

Main Results:

• C18-derivatized MALDI probe surfaces effectively isolate and desalt biopolymers.
• Quantitative MALDI enabled determination of peptide surface density on C18 probes.
• Peptide binding was found to be independent of analyte concentration (high to sub-ng/mL).
• Peptide binding was dependent on the immersion time of the probe surface in the analyte solution.

Conclusions:

• C18-derivatized MALDI probes function as efficient hydrophobic SPE devices for biopolymer analysis.
• The fixed binding capacity of these probes simplifies sample preparation by eliminating the need for serial dilution or vacuum drying.
• This approach significantly increases the overall efficiency and throughput of the MALDI technique.