title: Identification of low molecular weight organic acids by ion chromatography/hybrid quadrupole time-of-flight mass spectrometry during Uniblu-A ozonation.
abstract: BACKGROUND
  The balance of organic nitrogen and sulfur during ozonation of organic pollutants often shows a lack of complete mineralization. It follows that polar and ionic by-products are likely to be present that are difficult to identify by liquid chromatography/mass spectrometry (LC/MS).
  
  
  METHODS
  The structural elucidation of low molecular weight organic acids arising from Uniblu-OH ozonation has been investigated by ion chromatography/electrospray tandem mass spectrometry (IC/ESI-MS/MS) employing a quadrupole time-of-flight mass spectrometer. Unequivocal elemental composition of the by-products was determined by a combination of mass accuracy and high spectral accuracy.
  
  
  RESULTS
  The employed identification strategy was demonstrated to be a powerful method of unequivocally assigning a single chemical composition to each identified compound. The exact mass measurements of [M-H](-) ions allowed the elemental formulae and related structures of eighteen by-products to be determined confidently. The main degradation pathways were found to be decarboxylation and oxidation. The experimental procedure allowed the identification of both nitrogen- and sulfur-containing organic acid by-products arising from Uniblu-OH ozonation.
  
  
  CONCLUSIONS
  The obtained results are of environmental relevance for the balance of organic nitrogen and sulfur during the ozonation of organic pollutants due to the lack of complete mineralization of the compounds containing these atoms.
authors.affiliation: Istituto di Ricerca Sulle Acque, Consiglio Nazionale delle Ricerche, Viale F. De Blasio 5, 70132, Bari, Italy.
authors.forename: Apollonia
authors.initials: A
authors.lastname: Amorisco
authors.forename: Vito
authors.initials: V
authors.lastname: Locaputo
authors.forename: Carlo
authors.initials: C
authors.lastname: Pastore
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Mascolo