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Leveraging CI-H Mass Defect Plots for the Identification of Halogenated Organic Contaminants
EP22988
Poster Title: Leveraging CI-H Mass Defect Plots for the Identification of Halogenated Organic Contaminants
Submitted on 14 May 2015
Author(s): Jonathan D. Byer, Mehran Alaee, Karl Jobst, Grazina Pacepavicius, Joe Binkley
Affiliations: LECO Corporation, Environment Canada, Ontario Ministry of the Environment
This poster was presented at Dioxin 2014
Poster Views: 1,755
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Poster Information
Abstract: Time-of-flight mass spectrometry (TOFMS) is unsurpassed for non-target analysis because full range mass spectra are acquired simultaneously with minimal mass bias at acquisition rates suitable for narrow gas chromatographic peaks. This provides a number of advantages, including the possibility of deconvolving chromatographic interferences using modern software, further enhancing the ability to isolate and identify a greater number of compounds. Mass defect is the difference between the nominal and exact masses of a compound or its fragments. Halogenated compounds have characteristic mass defects and isotope patterns that make them readily distinguishable from most other compound classes.
Mass defect (Cl-H) can be calculated according to the following equations, where the IUPAC mass is the observed mass and the scaling factor for chlorine substituted for hydrogen equals 34/33.960479:
 
Cl-H Scaled Mass = IUPAC Mass × Scaling Factor
 
Cl-H Mass Defect = Cl-H Scaled Mass – Nominal Cl-H Scaled Mass
 
In this study we used non-target analysis in the form of Cl-H mass defect plots, to identify halogenated contaminants in eels (Anguillia rostrata) from Lake Ontario, Canada.
Summary: A number of legacy contaminants and other pesticides, as well as a number of previously unknown compounds were tentatively identified in the pooled sample. Cl-H mass defect plots are a useful tool for filtering through complex data for the identification of halogenated contaminants. This technique functions as a screening tool for the identification of unknowns, and in the future, may be used as a form of fingerprinting to compare samples.References: Sleno L. (2012); J Mass Spectrom. 47(2): 226-36
Taguchi VY, Nieckarz RJ, Clement RE, Krolik S, Williams R. (2010); JASMS. 21(11): 1918-21
Jobst KJ, Shen L, Reiner EJ, Taguchi VY, Helm PA, McCrindle R, Backus S. (2013); Anal Bioanal Chem. 405: 3289-97
Byer JD, Lebeuf M, Alaee M, Brown RS, Trottier S, Backus S, Keir M, Couillard CM, Casselman J, Hodson PV. (2013); Chemosphere. 90(5): 1719-28
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