Rapid Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry Imaging with Scanning Desorption Laser Beam

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF MS) imaging of surfaces and tissues is a rapidly evolving technique having great potential in the field of biosciences. In earlier times, acquisition of a single high-resolution MS image could take days. Despite the recent introduction of high-repetition rate lasers to increase sample throughput of axial TOF MS instruments, obtaining a high-resolution image still requires a few hours. This paper shows that a substantial increase in the throughput of the TOF MS-based tissue imaging can be achieved by incorporating a mirror providing highspeed precision scanning of the laser beam along the sample surface. Equipped with the scanning mirror, a laboratory-built axial MALDI TOF MS instrument utilizing a 4-kHz UV laser recorded a 100 x 100 pixel MS image in similar to 11 min using 100 laser shots per pixel. This is almost an order Of magnitude faster when compared to a modern commercial instrument equipped with 1-kHz laser.