Molecular Formula Identification by NMR

Molecular formulas were searched in ChemSpider database³² by tolerating plus or minus one hydrogen mass in each formula: for example, C₇H₁₅NO₃ is searched as C₇H_14-16NO₃. The following six elements were considered for the generation of the molecular formula from exact masses: C, H, N, O, P, and S. 2D ¹³C-¹H HSQC spectra of the returned structures are predicted by using MestReNova 9.0.1 (Mestrelab Research, Santiago de Compostela, Spain). HSQC prediction of each molecule takes about 10 seconds on a desktop computer. The comparison of each HSQC peak list of the experimental NMR spectra is performed by using the query algorithm of COLMAR ¹³C-¹H HSQC web server.^{33 (link)}