Latest generation LA-ICP-MS-based metallomic mapping has proven to be a powerful tool in aiding understanding of the spatial distribution and concentration of endogenous and exogenous elements and their consequent role in biological systems. For metallomic imaging in animal tissue, the preferred method of biological tissue sample preparation is the use of frozen samples (rather than FFPE) that are prepared by cryotome. Sections of 3-10 micron thickness are mounted onto glass slides and stored in a -60 to -80oC freezer. Prior to mapping analysis, samples are often defrosted and swiftly analysed to prevent complete desiccation. For plant tissue, samples are not generally fixed and are instead often freeze-dried. Unfortunately, the freeze drying process can result in altered or unstable structure, leading to loss of true spatial distribution of elements in the maps generated.

Some prior work has been performed with cryogenic sample chambers in an attempt to retain the moisture content of the sample at a steady-state during analysis.^{[1], [2]} Ablation of frozen phase samples may confer long- and short-term precision advantages and can enable the use of frozen standards for calibration, but reported results have not used latest generation low dispersion sample chambers that offer optimal lateral spatial resolution and higher scan speeds or latest generation ICP-TOF-MS that confers ultra-fast and pseudo-simultaneous detection of multiple elements.

This work presents preliminary data for the mapping of frozen plant tissue samples utilising a new low dispersion cryo sample chamber and ICP-TOF-MS allowing for high-repetition rate mapping on biological samples in cryogenic conditions. Multi-elemental maps recorded at <5 µm resolution showing interesting isotopic distributions will be shown.

References

[1] F. Li, et al, Anal and Bioanal Chem, 2023, 415, 6051-6061.

[2] I. Konz, et al, Anal and Bioanal Chem, 2014, 406, 2343-2348.