Desorption electrospray ionization mass spectrometry: advances in instrumentation, high-throughput analysis, and...

Desorption Electrospray Ionization (DESI) is a unique ambient ionization technique in mass spectrometry that operates under atmospheric pressure without the need for vacuum systems, chemical matrices, or extensive sample preparation. These characteristics distinguish DESI from conventional ionization methods and enable quasi on-demand molecular analysis directly from native surfaces and tissues, an analytical capability otherwise impractical for many time-sensitive or spatially constrained applications. Since its development by Cooks et al. in 2004, DESI-MS has become an indispensable method for both qualitative and quantitative applications. It operates by propelling charged microdroplets (typically <10 μm in diameter) onto sample surfaces, producing gas-phase ions through soft ionization. This review presents a critical evaluation of DESI performance across a range of uses, including surface profiling, molecular imaging, and in situ diagnostics. DESI-MS allows analysis rates exceeding 2 samples per second in formats such as 96-well plates, with detection limits in the low nanogram range. Imaging applications have demonstrated spatial resolutions below 200 μm, with scan speeds reaching 100 μm s^-1, enabling detailed molecular mapping in biological tissues. Technological advancements, such as infrared laser-assisted DESI (IR-LADESI), enclosed DESI modules, and microdroplet-driven reaction screening, have expanded DESI's applicability across pharmaceutical, clinical, forensic, and environmental fields. This review synthesizes developments from 2020 to 2025, emphasizing technical principles, instrumentation progress, and analytical performance, and positions DESI-MS as a leading tool in modern mass spectrometry.