Clarification of the 30 Da releases from the [M-H]~- and M~-? ions of trinitrotoluene by electrospray high resolution mass spectrometry

摘要

Although some nitroaromatic compounds can naturally occur in the environment, the vast majority of them come from anthropogenic sources. Indeed, nitroaromatic compounds such as 2,4,6-trinitrotoluene (TNT) and related-compounds are widely used as chemicals or synthetic intermediates in industrial manufacturing of explosives, dyes, pharmaceuticals, polyurethane foams and pesticides.~([1]) Considering the proven toxicity of nitroaromatic compounds on living organisms ~([2]) and their significance in the forensic sciences, much attention has been given to these compounds.~([3]) Thus, nitroaromatic compounds have been extensively studied by mass spectrometry (MS) coupled with different ionization sources. At first, classical vacuum ionization techniques such as electron ionization ~([4,5]) and chemical ionization (CI)~([5–7]) were widely used to examine nitroaromatic compounds. Upon the development of atmospheric pressure ionization (API) techniques, atmospheric pressure CI (APCI)~([8]) and electrospray ionization (ESI)~([9]) became established as the preferred techniques to analyze nitroaromatic compounds.[10] In particular, ESI of TNT in the negative ion mode can produce competitive processes: ~((i)) deprotonation [M-H]~- and ~((ii)) electrochemical reduction M?~-.~([11,12]) Afterwards, collision-induced dissociation (CID) has been extensively used for structural as well as quantitative information~([13]). TNT samples are commonly analyzed at low resolution by tandem MS. Under CID conditions, these negatively charged molecular species dissociate by competitive losses of either OH? (implicating the ‘ortho effect’, Scheme 1) or by loss of NO? (after NO_2/ONO isomerization). In addition, NO_2 ? release was also observed.