Using quantum-chemical methods, vibrational spectra can be routinely and accurately calculated (somewhat in contrast to MS/MS spectra). For example, Karunaratne et al. pursued identification of neutral gaseous molecules detected with GC-FTIR spectroscopy by employing DFT-calculated reference spectra of compounds extracted from the PubChem database . This approach yields identification rates comparable to those achieved with MS/MS. However, GC-FTIR is not compatible with typical sample matrices in the metabolomics field, where LC-MS is the method of choice.