This study evaluated the accuracy of NEIMS EI-MS spectral prediction for monosubstituted α-amino acids found within three spectral libraries: the National Institute of Standards and Technology's 2017 mass spectral dataset (NIST17), the Mass Bank of North America's Mass Spectral Database (MoNA) specifically filtered to exclude spectra also found within the NIST17 database (MoNA f ), and a hand curated set comprising GCMS spectra for amino acids outside NIST17 (hereinafter IOCB). NIST 17 comprises "a fully evaluated collection of electron ionization (EI) …mass spectra" .