Matrix phase fractionation: Investigating the compromise between dynamic range of analyte extraction and spatial resolution in mass spectrometry imaging.

Rationale: Matrix-assisted laser desorption ionisation with mass spectrometry imaging (MSI) has seen rapid development in recent years and as such is becoming an important technique for the mapping of biomolecules from the surface of tissues. One key area of development is the optimisation of analyte extraction by using modified matrices or mixes of common ones.

Methods: A series of serial sections were prepared for lipid MSI by either dry coating (sublimation) or by wet spray application of several matrices. These samples were then evaluated for analyte extraction, delocalisation and dynamic range.

Results: We have shown that the spraying and sublimation methods of matrix application can be used complementarily. This creates large datasets, with each preparation method applied narrowly and then interpreted as a 'fraction' of the whole. Once combined, the dynamic range is significantly increased. We have dubbed this technique 'matrix phase fractionation'.

Conclusions: We have found that, by utilising matrix phase fractionation for the detection of lipids in brain tissue, it is possible to create a significantly more comprehensive dataset than would otherwise be possible with traditional 'single-run' workflows.