Spot on: A Laser Micromachining-Based Approach to Improve Dried Matrix Spot Preparation with Proof-of-Principle...

Area of Science:

• Analytical Chemistry
• Mass Spectrometry
• Materials Science

Background:

• Dried matrix spots (DMSs) are increasingly used for sample storage and analysis, especially with ambient ionization mass spectrometry.
• Existing methods face challenges in precise liquid confinement and sample targeting.
• Advancements are needed to improve the efficiency and accuracy of DMS-based analyses.

Purpose of the Study:

• To present a novel laser micromachining approach for preparing targeted DMS substrates.
• To integrate these substrates with direct mass spectrometric analysis techniques.
• To address the limitations of liquid confinement and sample targeting in DMS preparation.

Main Methods:

• Laser micromachining was used to create hydrophobic paper substrates with surface energy traps (SETs) and visual reticles.
• DMSs were prepared on these SETs, significantly reducing spot size (down to 0.55 mm diameter).
• The targeted DMS substrates were analyzed using liquid microjunction-surface sampling probe-mass spectrometry (LMJ-SSP-MS) and flowing atmospheric-pressure afterglow-mass spectrometry (FAPA-MS).

Main Results:

• A laser-based method successfully produced DMSs on SETs with integrated visual reticles.
• The prepared DMSs were approximately 12 times smaller than traditional preparations.
• Caffeine was successfully detected in aqueous and artificial urine solutions using LMJ-SSP-MS and FAPA-MS, demonstrating the method's efficacy.

Conclusions:

• The laser micromachining approach offers precise targeting and reduced sample volume for DMS analysis.
• This method enhances visualization and analytical performance in mass spectrometry.
• Potential for automation using computer vision and robotics exists to further optimize analytical workflows.