As a microscale sampling and ionization device, the Single-probe can be coupled to MS for other studies. The Single-probe MS imaging (MSI) technique, first introduced in 2015, is a novel tool for analyzing biological tissues with high spatial under ambient conditions . During the MSI experiment, the Single-probe tip is placed closely above the tissue slice, and the solvent junction at the tip performs in-situ surface micro-extraction, and the extracted molecules are immediately analyzed by MS (Figure ). Using programmed stage control system, the Single-probe tip perform continuous raster sampling of the region of interest on tissue. MS images of ions of interest can be constructed using a visualization tool. The Single-probe is capable of producing MSI images with a spatial resolution as fine as 8.5 μm (Figure ), making it one of the highest resolutions among ambient MSI methods available. 4.3.1 Combining the Single-probe MSI with chemical reactions. Due its unique design, the sampling solvent of the Single-probe can be flexibly selected. Similar to the relevant application in SCMS studies , the use of dicationic compounds (i.e., [C5(bpyr)2F2] and [C3(triprp)2F2]) (Figure ) in MSI experiments enabled the detection of negatively charged species in the positive ion mode . Particularly, detection of metabolites in the m/z range of 600-900 was improved with enhanced ion intensities compared to regular negative ionization modes. This technique also allowed the detection of metabolites that were previously undetectable under standard conditions.