Figure 1.

Recent improvements pursued in liquid extraction ambient ionization MS technologies. The left panel shows the development and use of a newly designed DESI-MS spray source for improved analytical reproducibility and spatial resolution. A center disk within the spray nozzle is used to position the emitter more centrally within the source. A colorectal cancer tissue section was imaged with this source at three distinct spatial resolutions. A spatial resolution of 20 μm allowed for clear visualization of a small tumor region within the tissue (designated by an arrow). Adapted from Faster, More Reproducible DESI-MS for Biological Tissue Imaging (ref 17), J. Am. Soc. Mass Spectrom., Vol. 28, Issue 10, Tillner, J.; Wu, V.; Jones, E. A.; Pringle, S. D.; Karansci, T.; Dannhorn, A.; Veselkov, K.; McKenzie, J. S.; Takats, K. pp. 2090–2098, Copyright 2017, with permission from Elsevier. The center panel shows how a superhydrophobic-superhydrophilic patterning approach on a glass slide improved both liquid sample deposition and extraction with LESA-MS by preventing droplet dispersion. Improved analytical reproducibility was achieved with this system. Using this approach, an increased number of detected species that exhibited significantly altered signal intensity between the urine of participants before and after tea consumption were detected. Reproduced from Meurs, J.; Alexander, M. R.; Levkin, P. A.; Widmaier, S.; Bunch, J.; Barret, D. A.; Kim, D. Anal. Chem. 2018, 90, 6001–6005 (ref 23). Copyright 2018 American Chemical Society. The right panel shows how the modification of a paper substrate with MOFs, specifically UiO-66(Zr), can improve the detection of the blood pressure medication Verapamil and the antipsychotic Quetiapine in dried blood spots (DBS) using PSI. Reproduced from Wang, X.; Zheng, Y.; Wang, T.; Xiong, X.; Fang, X.; Zhang, Z. Anal. Methods 2016, 8, 8004–8014 (ref 24), with permission of The Royal Society of Chemistry.