1D-O2-1800 PDF
Ab Initio Study on Fragmentation Mechanism in MALDI Mass Spectra for Analysis of Hindered Amine Light Stabilizer I. Dimethyl Succinate Polymer with 4-Hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol
The fragmentation mechanisms in protonated molecule of dimethyl succinate-4- hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol polymer (Tinuvin 622) were investigated using MALDI MS/MS, ab initio DFT and semi-empirical PM6 MO methods. Two series of fragment peaks were observed at intervals of 283-Da in MALDI mass spectra of Tinuvin 622. The potential energy surfaces for the formation of m/z 216 ions were calculated with both stepwise and concerted mechanism. The barrier energy for the fragmentation process by the stepwise mechanism calculated using B3LYP/6-31G(d) was 71.7 kJ/mol smaller than that of the concerted mechanism.