The combination of chiral derivatization and ion mobility-mass spectrometry provides the first insights into the separation of 19 pairs of chiral proteinogenic d/l-amino acids in a single run and detection of chiral amino acids in complex samples.

Fine particulate matter (PM2.5) exposure remains a great health risk worldwide. Epidemiological evidence suggests a possible association between neurodegeneration and PM2.5 exposure. In the present study, cutting-edge mass spectrometry imaging techniques were implemented to investigate the spatial distribution of lipids in rat brains after real ambient exposure to air with high PM2.5 levels. For the first time, a significant reduction of sulfatides in the brain stem and corpus callosum of PM-exposed rats was observed. Further validation using isolated corpus callosum tissues showed that in addition to decreased sulfatides expression levels of neuroinflammation markers including cytokines, microglial, and astrocyte activation markers were significantly upregulated in the PM-exposure group. Our data, therefore, provides a possible association between PM exposure and neurological damage, via sulfatides reduction and associated neuroinflammation in the corpus callosum region of PM-exposed rat brains.

The importance of chiral amino acids (AAs) in living organisms has been widely recognized since the discovery of endogenous D-AAs as potential biomarkers in several metabolic disorders. Chiral analysis by ion mobility spectrometry-mass spectrometry (IMS-MS) has the advantages of high speed and sensitivity but is still in its infancy. Here, a Nα-(2,4-dinitro-5-fluorophenyl)-L-alaninamide (FDAA) derivatization is combined with trapped ion mobility spectrometry-mass spectrometry (TIMS-MS) for chiral AA analysis. For the first time, we demonstrate the simultaneous separation of 19 pairs of chiral proteinogenic AAs in a single fixed condition TIMS-MS run. The utility of this approach presents for mouse brain extracts by direct-infusion TIMS-MS. The robust separation ability in complex biological sample was proven in MALDI TIMS mass spectrometry imaging (MSI) as well by directly depositing 19 pairs of AAs on a tissue slide following on-tissue derivatization. In addition, endogenous chiral amino acids were also detected and distinguished. The developed methods show compelling application prospects in biomarker discovery and biological research.Entry for the Table of ContentsThe combination of chiral derivatization and trapped ion mobility-mass spectrometry provides the first insights into the separation of 19 pairs of chiral proteinogenic D/L-amino acids in a single run and further visualization of chiral amino acids under complex biological matrix.