Mass spectrometry imaging for environmental sciences: A review of current and future applications

High resolution mass spectrometry has long been employed in environmental research to identify and quantify contaminants, biological metabolites, and abiotic sample constituents with high selectivity afforded by mass-based detection. Many mass spectrometry-based techniques require that the sample be homogenized prior to analysis, thereby eliminating the possibility of assessing the spatial distribution of analytes and preventing information regarding pollutant fate and uptake in various matrices. High-resolution mass-spectrometry imaging provides the unique opportunity to obtain two-dimensional information of unlabeled analytes of interest to identify their presence or absence, assess their fate and uptake within biotic and abiotic samples, and visualize the relative changes of endogenous compounds following pollutant exposure. Some researchers have begun demonstrating the power of HR-MSI for environmental applications, although the technique is still new and yet to be fully actualized. This review will highlight the current status of HR-MSI in environmental research through discussions of non-target analysis and suspect screening, assessment of wastewater treatment plant constituents, and PFAS toxicology, and an introduction to emerging applications.