title: Understanding of the mass spectrometric fragmentation pathways of a few potentially genotoxic haloaniline isomers in their protonated form by collision-induced dissociation.
abstract: Collision-induced dissociation (CID) mass spectra of a few haloaniline isomers, (chloroanilines, dichloroanilines, difluoroanilines, chloro-fluoroanilines and bromo-fluoroanilines) were characterized. The mass spectral behaviour of difluoroanilines was different from those of the corresponding regioisomers of the other haloanilines. For all ortho regioisomers except difluoroanilines, CID mass spectra resulted in hydrogen halide as well as halogen radical loss. In the case of difluoroanilines, peaks corresponding to hydrogen fluoride loss were observed during the same process. Meta and para-haloanilines have the tendency to lose either ammonia or halogen radicals. Six regioisomers of dichloroanilines were subjected to hydrogen/deuterium exchange experiments in solution to determine the CID fragmentation pathways. From the experimental results we propose two fragmentation pathways for the dicholoroanilines: (a) formation of aza-biheterocyclic intermediate and (b) via heterolytic hydrogen transfer from the charged center. The demonstrated unique characteristics in CID mass fragmentation of haloanilines may be useful in identification and differentiation of isomers as impurities during chemical process development. A good use of the ortho effect is the significant differentiation between 2-chloro-4-fluoroaniline and 4-chloro-2-fluoroaniline by CID mass spectra.
authors.affiliation: Analytical Sciences, Pharmaceutical Development, AstraZeneca India Pvt Limited, Bangalore 560024, India. rex.patrick@astrazeneca.com
authors.forename: Rex
authors.initials: R
authors.lastname: Patrick
authors.forename: N S
authors.initials: NS
authors.lastname: Nagarajan
authors.forename: Hefeng
authors.initials: H
authors.lastname: Pan
authors.forename: Subhra Kanti
authors.initials: SK
authors.lastname: Saha
authors.forename: Jayan
authors.initials: J
authors.lastname: Rapai
authors.forename: Venkatarao
authors.initials: V
authors.lastname: Torlikonda
authors.forename: Manoranjan
authors.initials: M
authors.lastname: Panda
authors.forename: Sulur G
authors.initials: SG
authors.lastname: Manjunatha
authors.forename: Sudhir
authors.initials: S
authors.lastname: Nambiar
mesh_terms: D000814:Aniline Compounds / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D004249:DNA Damage; D003903:Deuterium / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D007536:Isomerism; D013058:Mass Spectrometry; D009153:Mutagens / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D011522:Protons; D012984:Software
chemical_list: D000814:Aniline Compounds; D009153:Mutagens; D011522:Protons; C066212:2-fluoroaniline; C043455:4-fluoroaniline; D003903:Deuterium