Gas-Phase Adsorption of N(2) on Protonated Molecules and Its Application to the Structural Elucidation of Small Molecules

The gas-phase adsorption of N(2) on protonated serine (Ser, C(3)H(7)NO(3)), threonine (Thr, C(4)H(9)NO(3)), glycine (Gly, C(2)H(5)NO(2)), and 2-aminoethanol (C(2)H(7)NO) was investigated using a tandem mass spectrometer equipped with an electrospray ionization source and a cold ion trap. N(2) molecules were adsorbed on the free X–H (X=O and N) groups of protonated molecules. Gas-phase N(2) adsorption-mass spectrometry detected the presence of free X–H groups in the molecular structures, and was applied to the structural elucidation of small molecules. When the 93 structures with an elemental composition of C(3)H(7)NO(3) were filtered using the gas-phase N(2) adsorption-mass spectrometry results for Ser, the number of possible molecular structures was reduced to 8 via the quantification of the X–H groups. Restricting and minimizing the number of possible candidates were effective steps in the structural elucidation process. Gas-phase N(2) adsorption-mass spectrometry combined with mass spectrometry-based techniques has the potential for being useful for elucidating the molecular structures of a variety of molecules.