![Sample our Environment & Agriculture journals, sign in here to start your access, latest two full volumes FREE to you for 14 days]({"type":"image" , "src" : "/sda/5934/TOC-Subject-Sample-2021-Environment-Agriculture.jpg"})
ABSTRACT
Isomers are compounds with the same molecular formula. Many different types of isomers are ubiquitous and play important roles in living organisms. Despite their early discovery, the actual analysis of isomers has been tricky and has confounded researchers. Using mass spectrometry (MS) to distinguish or identify isomers is an emergent topic and challenge for analytical chemists. We review some techniques for analyzing isomers with emphasis on MS, e.g., the roles of ion reaction, hydrogen–deuterium exchange, ion mobility mass spectrometry, ion spectroscopy, and energy change in producing isomer-specific fragments. In particular, soft ionization for gas chromatography–mass spectrometry (GC–MS) is a focus in this review. Awareness of the advantages and technical problems of these techniques would inspire innovation in future approaches.
Abbreviations
| AIMS | = | Aspiration ion mobility spectrometry |
| APCI | = | Atmospheric pressure chemical ionization |
| API | = | Atmospheric pressure ionization |
| APPI | = | Atmospheric pressure photoionization |
| CCS | = | Collision cross section |
| CDI | = | Corona discharge ionization |
| CE | = | Capillary electrophoresis |
| CI | = | Chemical ionization |
| CID | = | Collision induced dissociation |
| CSP | = | Chiral stationary phases |
| DART | = | Direct analysis in real time |
| DT-IMS | = | Drift time ion mobility spectrometry |
| ECD | = | Electron capture dissociation |
| ETD | = | Electron transfer dissociation |
| EI | = | Electron ionization |
| ESI | = | Electrospray ionization |
| FAB | = | Fast atom bombardment |
| FAIMS | = | Field asymmetric ion mobility spectrometry |
| FD | = | Field desorption |
| FELIX | = | Fourier transform ion cyclotron resonance mass spectrometer |
| FI | = | Field ionization |
| FT | = | Fourier transform |
| FT-ICR | = | Fourier transform ion cyclotron resonance |
| GC | = | Gas chromatography |
| HILIC | = | Hydrophilic interaction liquid chromatography |
| HPLC | = | High performance liquid chromatography |
| IMS | = | Ion mobility spectrometry |
| IR | = | Infra-red (spectroscopy) |
| IRD | = | Infra-red dissociation |
| IRMPD | = | Infrared multiphoton dissociation |
| IT | = | Ion trap |
| LC | = | Liquid chromatography |
| LDI | = | Laser desorption ionization |
| LV-EI | = | Lower voltage electron ionization |
| MALDI | = | Matrix assisted laser desorption ionization |
| MS | = | Mass spectrometry |
| NMR | = | Nuclear magnetic resonance |
| ODS | = | Octadecyl-silica |
| OPO | = | Optical parametric oscillator |
| PAD | = | Photo diode array detector |
| PAH | = | Polycyclic aromatic hydrocarbon |
| PCB | = | Polychlorinated biphenyl |
| PD | = | Photo dissociation |
| PES | = | Photoelectron spectroscopy |
| PI | = | Photo ionization |
| PUFA | = | Polyunsaturated fatty acid |
| REMPI | = | Resonance-enhanced multiphoton ionization |
| RID | = | Refractive index detector |
| RI | = | Radioactive ionization |
| SEC | = | Size exclusion chromatography |
| SFC | = | Supercritical fluid chromatography |
| SRM | = | Selected reaction monitoring |
| TIMS | = | Trapped ion mobility spectrometry |
| TLC | = | Thin-layer chromatography |
| TMS | = | Trimethylsilyl |
| ToF | = | Time-of-flight |
| TW-IMS | = | Traveling wave ion mobility spectrometry |
| UV/Vis | = | Ultraviolet/visible light |
| vdW | = | van der Waals |
| VUV | = | Vacuum ultraviolet light |
| WCOT | = | Wall-coated open-tubular |
| ZEKE | = | Zero-electron kinetic energy |
Acknowledgments
We thank Dr. Nakamura (RIKEN) for giving us useful comments and kind encouragement. Dr. Stachowitsch improved the English of an early draft. Hamamatsu Photonics Company provided photos of the VUV lump.
