Applications of ambient ionization mass spectrometry in 2020: an annual review

Recent developments in mass spectrometry (MS) analyses have seen a concerted effort to reduce the complexity of analytical workflows through the simplification (or removal) of sample preparation and the shortening of run‐to‐run analysis times. Ambient ionization mass spectrometry (AIMS) is an exemplar MS‐based technology that has swiftly developed into a popular and powerful tool in analytical science. This increase in interest and demonstrable applications is down to its capacity to enable the rapid analysis of a diverse range of samples, typically in their native state or following a minimalistic sample preparation approach. The field of AIMS is constantly improving and expanding, with developments of powerful and novel techniques, improvements to existing instrumentation, and exciting new applications added with each year that passes. This annual review provides an overview of applications of AIMS techniques over the past year (2020), with a particular focus on the application of AIMS in a number of key fields of research including biomedical sciences, forensics and security, food sciences, the environment, and chemical synthesis. Novel ambient ionization techniques are introduced, including picolitre pressure‐probe electrospray ionization and fiber spray ionization, in addition to modifications and improvements to existing techniques such as hand‐held devices for ease of use, and USB‐powered ion sources for on‐site analysis. In all, the information provided in this review supports the view that AIMS has become a leading approach in MS‐based analyses and that improvements to existing methods, alongside the development of novel approaches, will continue across the foreseeable future.