ROUTINE COMPREHENSIVE TISSUE IMAGING ON THE XEVO G3 QTOF MASS SPECTROMETER USING DESI XS

Importance of the Topic

Spatially resolved mass spectrometry imaging of tissue sections enables detailed mapping of molecular distributions, which is critical for understanding biological heterogeneity in neuroscience and pathology. Enhancing acquisition speed without compromising data quality addresses a major bottleneck in routine MSI workflows.

Study Objectives and Overview

This study evaluates the impact of varying DESI imaging scan rates on data quality using the Waters Xevo G3 QTof mass spectrometer. By comparing tissue segmentation, lipid correlation metrics, and mass performance across scan speeds from 2 to 20 scans per second, the goal is to establish optimal parameters for high-throughput MSI.

Methodology

A murine brain was cryosectioned to 18µm and analyzed by DESI MSI in MS mode over m/z 50–1200. Key acquisition settings included:

• Capillary voltage: 0.6 kV
• Nebulizing gas flow: 15 psi
• Solvent: 98% methanol/2% water at 2 µL/min
• Transfer line temperature: 450 ℃
• Pixel size: 50 µm; step rates of 100, 250, 500, 1000 µm/s yielding 2, 5, 10, 20 sps

Data was reviewed in MassLynx and processed in High Definition Imaging using UMAP and HDBSCAN for spectral segmentation.

Used Instrumentation

• Waters Xevo G3 QTof mass spectrometer
• DESI XS ion source with high-performance sprayer and heated transfer line
• MassLynx software
• High Definition Imaging (HDI) software

Main Results and Discussion

Segmentation maps remained consistent across scan rates, accurately delineating brain structures, with R2 values >0.97 for biological replicates. Correlation of lipid intensities between speeds exceeded 0.949. Unsupervised PCA of regions of interest showed negligible separation due to scan rate. Mass resolution (~30,000 FWHM) and mass accuracy were maintained at higher acquisition speeds, indicating minimal compromise in spectral quality.

Benefits and Practical Applications

Increasing MSI throughput by up to tenfold accelerates data acquisition for large studies and routine QA/QC without sacrificing spatial or spectral fidelity. This robustness supports rapid biomarker discovery and high-volume pharmaceutical analyses.

Future Trends and Prospects

Advancements may include integration of MS/MS or SONAR modes for structural insights, automated data processing pipelines, machine learning–driven segmentation, and further optimization of high-speed imaging for clinical and industrial applications.

Conclusion

High-speed DESI MSI on the Xevo G3 QTof platform enables rapid, high-quality tissue imaging. The study demonstrates that increased scan rates have negligible impact on data consistency, supporting routine deployment in diverse analytical workflows.