title: Two sensitizing oxidation products of p-phenylenediamine patch tested in patients allergic to p-phenylenediamine.
abstract: BACKGROUND
  The results from a previous study indicated the presence of several possible sensitizers formed during oxidation of the potent sensitizer p-phenylenediamine (PPD) to which PPD-sensitized patients might react, in various patterns.
  
  
  OBJECTIVE
  To extract and analyse a yellow spot from a thin-layer chromatogram with oxidized PPD, to which 6 of 14 (43%) PPD-positive patients had reacted in a previous study, in order to identify potential sensitizer(s) and to patch test this/these substance(s) in the 14 PPD-positive patients.
  
  
  METHODS
  The yellow spot was extracted from a thin-layer chromatogram of oxidized PPD, and two substances, suspected to be allergens, were identified by analysis with gas chromatography mass spectrometry (GCMS). The 14 PPD-positive patients, who had been previously tested with the thin-layer chromatogram of oxidized PPD, participated in the investigation, and were tested with dilutions of the two substances.
  
  
  RESULTS
  GCMS analysis identified 4-nitroaniline and 4,4'-azodianiline in the yellow spot. Of the 14 PPD-positive test patients, 5 (36%) reacted to 4-nitroaniline and 9 (64%) reacted to 4,4'-azodianiline.
  
  
  CONCLUSIONS
  The results show that 4-nitroaniline and 4,4'-azodianiline, formed during oxidation of PPD, are potent sensitizers. PPD-sensitized patients react to a high extent to concentrations equimolar to PPD of 4-nitroaniline and 4,4'-azodianiline.
authors.affiliation: Department of Occupational and Environmental Dermatology, Skåne University Hospital, Lund University, 205 02, Malmö, Sweden.
authors.forename: Ewa
authors.identifier: http://orcid.org/0000-0001-5172-8323
authors.initials: E
authors.lastname: Young
authors.affiliation: Department of Occupational and Environmental Dermatology, Skåne University Hospital, Lund University, 205 02, Malmö, Sweden.
authors.forename: Erik
authors.initials: E
authors.lastname: Zimerson
authors.affiliation: Department of Occupational and Environmental Dermatology, Skåne University Hospital, Lund University, 205 02, Malmö, Sweden.
authors.forename: Magnus
authors.initials: M
authors.lastname: Bruze
authors.affiliation: Department of Occupational and Environmental Dermatology, Skåne University Hospital, Lund University, 205 02, Malmö, Sweden.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Svedman
mesh_terms: D017449:Dermatitis, Allergic Contact / Q000175:diagnosis / Q000209:etiology*; D006202:Hair Dyes / Q000009:adverse effects*; D006801:Humans; D010328:Patch Tests; D010655:Phenylenediamines / Q000009:adverse effects*
chemical_list: D006202:Hair Dyes; D010655:Phenylenediamines; C007303:2,5-diaminotoluene; C029728:4-phenylenediamine
keywords: 4,4′-azodianiline; 4-nitroaniline; PPD; allergic contact dermatitis; gas chromatography; hair dye; oxidation products; thin-layer chromatogram