title: Development of a liquid chromatographic method based on ultraviolet-visible and electrospray ionization mass spectrometric detection for the identification of nitrocatechols and related tracers in biomass burning atmospheric organic aerosol.
abstract: BACKGROUND
  Studying the chemical composition of biomass burning aerosol (BBA) is very important in order to assess their impact on the climate and the biosphere. In the present study, we focus on the characterization of some newly recognized biomass burning aerosol tracers including methyl nitrocatechols, nitroguaiacols and 4-nitrocatechol, but also on nitrophenols, methyl nitrophenols and nitrosalicylic acids, using liquid chromatography tandem mass spectrometry.
  
  
  METHODS
  For the purpose of their separation and detection in atmospheric aerosol, a new chromatographic method was initially developed based on reversed-phase chromatography coupled with ultraviolet/visible (UV/Vis) detection. The method was afterwards transferred to a liquid chromatography/electrospray ionization linear ion trap mass spectrometry (LC/ESI-LITMS) system in order to identify the targeted analytes in winter aerosol from the city of Maribor, Slovenia, using their chromatographic retention times and characteristic (-)ESI product ion (MS(2) ) spectra.
  
  
  RESULTS
  The fragmentation patterns of analytes obtained with LITMS are presented. Additional nitro-aromatic compounds (m/z 168 and 182) closely related to the targeted nitrocatechols and nitroguaiacols were detected in the aerosol. According to their MS(2) spectra these compounds could be attributed to methyl homologues of methyl nitrocatechols and nitroguaiacols.
  
  
  CONCLUSIONS
  The proposed LC/MS method results in a better separation and specificity for the targeted analytes. Several nitro-aromatic compounds were detected in urban BBA. The LC/MS peak intensity of the newly detected methyl nitrocatechols and nitroguaiacols is comparable to that of the methyl nitrocatechols, which also qualifies them as suitable molecular tracers for secondary biomass burning aerosol.
authors.affiliation: Laboratory for Analytical Chemistry, National Institute of Chemistry, Ljubljana, Slovenia. zoran.kitanovski@ki.si
authors.forename: Zoran
authors.initials: Z
authors.lastname: Kitanovski
authors.forename: Irena
authors.initials: I
authors.lastname: Grgić
authors.forename: Farhat
authors.initials: F
authors.lastname: Yasmeen
authors.forename: Magda
authors.initials: M
authors.lastname: Claeys
authors.forename: Alen
authors.initials: A
authors.lastname: Cusak
mesh_terms: D000336:Aerosols / Q000737:chemistry; D018533:Biomass; D002396:Catechols / Q000032:analysis*; D055598:Chemical Phenomena; D056148:Chromatography, Reverse-Phase / Q000379:methods*; D006139:Guaiacol / Q000032:analysis*; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D000432:Methanol; D009574:Nitro Compounds / Q000032:analysis*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry
chemical_list: D000336:Aerosols; D002396:Catechols; D009574:Nitro Compounds; C506350:nitrocatechol; D006139:Guaiacol; D000432:Methanol