Influences of Pyrolysis Conditions on the Major Pyrolytic Products of Asparagine

KeyWord:asparagine  Py/GC-MS  pyrolysis conditions  influence

Abstract:

      In this study£¬the pyrolysis vapors of asparagine under different pyrolytic conditions were analyzed by analytical pyrolysis/gas chromatography-mass spectrometry(Py/GC-MS).In addition£¬by using the amide 15N labeled asparagine sample and analysis of label incorporation of the major nitrogen contained compounds£¬the influence of pyrolysis conditions on the formation pathways of the major pyrolysis products of asparagine were elucidated.The results indicated that pyrolysis temperature has a significant impact on the decomposition of asparagine.The yields of major products at low and high temperature are strikingly different.The yields of maleimide and succinimide£¬which are the predominant pyrolysis products of asparagine£¬increased strikingly as the pyrolysis temperature increased from 300 ¡æ to 600 ¡æ£¬while in contrast£¬from 600 ¡æ to 900 ¡æ£¬the peak area of maleimide increased slowly but succinimide starts to decrease.The yields of amides and acidic compounds increased monotonically with the increase of the pyrolysis temperature£¬and the formation of nitriles and pyrroles were favored at higher heating temperatures.Furthermore£¬pyrolysis temperature has a significant effect on the formation pathways of the major pyrolysis products of asparagine.Most of the nitrogen in maleimide and acetamide originate from the 15N-labeled amide group of asparagine at low temperature£¬while from the unlabeled amino group at high temperature.The nitrogen atoms of the three nitrile compounds£¬hydrogen cyanide£¬acetonitrile and acrylonitrile are mainly from the unlabeled amino group£¬especially at higher temperature.By contrast£¬the influences of pyrolysis atmosphere and time on the yields and formation pathways of the major products of asparagine are much less.