Application of MS Imaging to Food Science and Safety Using the MALDI-8020 Benchtop MALDI- TOF Mass Spectrometer

Significance of the Topic

Mass spectrometry imaging (MSI) directly maps molecular distributions on surfaces without labels or derivatization, offering critical insights into residue localization in food and industrial materials. By providing spatially resolved chemical information, MSI supports food safety assessments, environmental monitoring, and material quality control.

Study Objectives and Overview

This work demonstrates the application of a benchtop MALDI-TOF instrument (MALDI-8020) for high-resolution MSI in two contexts: pesticide residue distribution on soybean seeds and heat-induced oligomer formation on polyethylene terephthalate (PET) film. The study aims to evaluate whether rapid MSI workflows can reveal surface and subsurface chemical heterogeneities relevant to food science and safety.

Methodology

Samples were prepared under controlled conditions and coated with matrix for MALDI analysis. Soybean seeds sprayed with an undisclosed pesticide were cryo-sectioned, then sublimation-coated with α-cyano-4-hydroxycinnamic acid (CHCA) using an automated vapor deposition system. PET films were heated at 175 °C for 0, 4, and 18 hours, then manually sprayed with a dithranol/NaI matrix solution. Imaging experiments used a 50 µm raster step and positive-ion linear MALDI-TOF acquisition. Data processing and image rendering were performed with proprietary software (IonView™ for seeds, IMAGEREVEAL™ MS for PET).

Used Instrumentation

• MALDI-8020 benchtop linear MALDI-TOF mass spectrometer
• iMLayer™ automated matrix vapor deposition system
• Manual matrix sprayer for dithranol/NaI coating
• IonView™ and IMAGEREVEAL™ MS imaging software

Main Results and Discussion

In the seed study, MSI revealed that the pesticide signal localized exclusively to the seed surface, while a putative metabolite distributed heterogeneously within internal tissues. Overlay images confirmed distinct patterns of parent compound and metabolite. For PET films, the cyclic trimer [M+Na]+ at m/z 599.3 was detected at increasing intensity after heating. After 4 hours, the trimer signal was uniformly present; after 18 hours, it concentrated in the lower regions of the excised film circles. Such intensity mapping provides rapid visualization of heat-induced degradation products across surfaces.

Benefits and Practical Applications

MSI with a benchtop MALDI-TOF offers:

• Rapid, label-free surface analysis at 50 µm resolution
• Visualization of pesticide penetration and metabolite formation in seeds
• Characterization of oligomer distribution in food-contact polymers
• Data to inform safe pesticide application and material processing

Future Trends and Opportunities

Advances in matrix deposition automation, higher spatial resolution, and quantitative MSI will expand applications in food authentication, packaging safety, and environmental residue monitoring. Combining MSI with complementary imaging modalities and machine learning-driven analysis promises deeper insights into complex matrices. Portable or fully integrated platforms may enable in-line QC in manufacturing and field-based screening.

Conclusion

This study validates the MALDI-8020 benchtop MALDI-TOF system for rapid, high-resolution MSI in food science and safety contexts. The approach delivers spatially resolved chemical maps of pesticides and polymer oligomers, supporting informed decision-making in environmental protection and material quality control.