While this could work for specific applications with targeted analytes of interest, this approach will always be incremental given the current broad applicability of NEIMS. With this in mind, our findings further display the need to optimize existing ab initio prediction algorithms (e.g. QCxMS ) for larger molecules. If GCMS spectra prediction could readily be trusted for any molecule, even for those outside of a ML algorithm's training set, then reliable databases could be curated for any structures currently missing spectra, even theoretical molecules (e.g. AACL amino acid library ).