高密度試料スポット技術のレーザー脱離イオン化質量分析への応用

Abstract

Novel aspects of laser desorption/ionization mass spectrometry were demonstrated using a recently developed 8-ch capillary-based dispensing workstation with a variable capillary pitch mechanism. Its application to improve mass accuracy in external mass calibration for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) was investigated using angiotensin-I, as both of reference and sample compounds positioned close to each other on a target plate. The workstation's high-density dispensing was found to provide an 8×8 spot array, with a spot interval of 1 mm, and a standard deviation of mass errors of 0.02 (16 ppm) for 64 spots in the array. Thus, the mass accuracy was comparable to that normally observed in internal mass calibration. The workstation was also applied to dispensing small volumes of sample solutions of octylphenol polyethoxylate and α-cyclodextrin with high-density to substrates with self-assembled germanium nanodots (GeNDs) for surface-assisted laser desorption/ionization (SALDI). An 8×8 spot array, with a spot interval of 1 mm, was successfully prepared on the GeND substrates. Previously, this process required difficult preparation of multiple spots, either by dispensing them manually, or using conventional dispensers based on pipette tips.