title: Stable chlorine isotope analysis of chlorinated acetic acids using gas chromatography/quadrupole mass spectrometry.
abstract: BACKGROUND
  The environmental occurrence of chlorinated acetic acids (CAAs) has been extensively studied, but the sources and transport are still not yet fully understood. A promising approach for source apportionment and process studies is the isotopic characterization of target compounds. We present the first on-line stable chlorine isotope analysis of CAAs by use of gas chromatography/quadrupole mass spectrometry (GC/qMS).
  
  
  METHODS
  Following approved procedures for concentration analysis, CAAs extracted into MTBE were methylated to GC-amenable methyl esters (mCAAs). These mCAAs were then analyzed by GC/qMS for their stable chlorine isotope composition using a sample/standard-bracketing approach (CAA standards in the range δ(37) Cl -6.3 to -0.2 ‰, Standard Mean Ocean Chloride).
  
  
  RESULTS
  Cross-calibration of the herein presented method with off-line reference methods (thermal ionization and continuous-flow GC isotope ratio mass spectrometry; TI-MS and CF-GC/IRMS, respectively) shows good agreement between the methods (regression slope for GC/qMS vs reference method data sets: 0.92 ± 0.29). Sample amounts as small as 10 pmol Cl can herewith be analyzed with a precision of 0.1 to 0.4 ‰.
  
  
  CONCLUSIONS
  This method should be useful for environmental studies of CAAs at ambient concentrations in precipitations (<0.06 to 100 nmol L(-1) ), surface waters (<0.2 to 5 nmol L(-1) ) and soil (<0.6 to 2000 nmol kg(-1) dry soil) where conventional off-line methods cannot be applied.
authors.affiliation: Department of Environmental Science and Analytical Chemistry, Stockholm University, Stockholm, Sweden.
authors.forename: Milena E
authors.identifier: http://orcid.org/0000-0003-3096-9405
authors.initials: ME
authors.lastname: Miska
authors.affiliation: Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, Ontario, Canada.|Isotope Tracer Technologies Inc, Waterloo, Ontario, Canada.
authors.forename: Orfan
authors.initials: O
authors.lastname: Shouakar-Stash
authors.affiliation: Department of Environmental Science and Analytical Chemistry, Stockholm University, Stockholm, Sweden.
authors.forename: Henry
authors.initials: H
authors.lastname: Holmstrand
mesh_terms: D000085:Acetates / Q000032:analysis* / Q000737:chemistry*; D002713:Chlorine / Q000032:analysis*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D054879:Halogenation; D007554:Isotopes / Q000032:analysis*
chemical_list: D000085:Acetates; D007554:Isotopes; D002713:Chlorine