High Definition Imaging (HDI) 1.4: Lock Mass Recalibration for MS Imaging Data Sets

Importance of Mass Recalibration in MS Imaging

Mass accuracy is essential for reliable molecular identification in mass spectrometry imaging workflows. Calibration drift due to environmental fluctuations or long acquisitions can impair data quality and hamper subsequent analysis.

Study Objectives and Overview

This brief highlights the integration of external and internal lock mass recalibration features into High Definition Imaging Software version 1.4. The external approach uses pre deposited calibrants in MALDI MSI while the internal approach selects endogenous peaks for both MALDI and DESI MSI.

Methodology and Instrumentation

• Data acquired on orthogonal acceleration time of flight instruments
• Recalibration implemented within HDI Software v1.4 processing platform
• External lock mass via fixed sampling frequency and duration prior to acquisition
• Internal lock mass using a ubiquitous lipid peak at m/z 772.5254 with adjustable frequency and duration

Main Results and Discussion

Both internal and external recalibration methods effectively corrected uniform mass drift across the mass range. Internal recalibration in DESI MSI reduced mass errors around the targeted lipid peak. Comparative analysis in MALDI MSI demonstrated similar performance of both calibration strategies, even for heterogeneous samples lacking endogenous standards.

Benefits and Practical Applications

• Improved confidence in accurate mass assignments for database driven identification
• Seamless application across MALDI and DESI imaging modalities
• Flexibility to select external calibrants or endogenous markers
• Robust correction of drift during prolonged imaging runs

Future Trends and Opportunities

Emerging developments may include real time recalibration during acquisition workflows, use of multiple lock masses for enhanced coverage, application to new ionization techniques and adaptive recalibration algorithms for improved resilience.

Conclusion

The new lock mass recalibration capabilities in HDI Software v1.4 offer a reliable solution to maintain high mass accuracy in MSI data. Both external and internal approaches deliver comparable performance, enhancing data quality and facilitating confident molecular identification.