Electrospray Ionization Ion Mobility Spectrometry of Amino Acids: Ion Mobilities and a Mass−Mobility Correlation

As part of an ongoing effort to explore the utility of high-resolution electrospray ionization ion mobility spectrometry (ESI-IMS) for the detection and identification of organic molecules on other planetary bodies, pursuant to NASA objectives, the reduced ion mobilities of 14 amino acids that have been identified in meteoritic material were determined in both N 2 and CO 2 drift gases. A (12,4) hard core potential model of the ion−neutral interaction was applied to a combined data set of amino acid mobilities from the present work (abiotic) and an earlier investigation of twenty common biotic amino acids (Beegle, L. W.; Kanik, I.; Matz, L.; Hill, H. H. Anal. Chem. 2001, 73, 3028−3034). The model was used to investigate the protonated amino acid mass−mobility correlation to extract details of the ion−neutral interaction and to gain insight into the structural details of these ions.