When a picture is worth a thousand words: Molecular and elemental imaging applied to environmental analysis – A review

As spectral imaging is gaining special attention in the last years, once it allows transforming the chemical information from a sample surface into a high-resolution image of elemental and/or molecular spatial distribution. Then, this review aims to describe fundamental aspects of the main techniques applied to molecular and elemental imaging, such as mass spectrometry (MALDI-MS, DESI-MS, SIMS, and LA-ICP-MS) and optical spectroscopy (LIBS, Raman, and SXRF). Their advances, limitations, and potential to be used in environmental applications, such as environmental pollution and toxicity evaluation of pesticides, microplastics, nanoparticles, and emergent pollutants, are presented. A multimodal strategy based on combining these techniques is also discussed.