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Deconvolution of Mass Spectral Interferences of Chlorinated Alkanes and Their Thermal Degradation Products: Chlorinated Alkenes
journal contribution
posted on 2017-05-24, 11:35 authored by Lena Schinkel, Sandro Lehner, Norbert V. Heeb, Peter Lienemann, Kristopher McNeill, Christian BogdalChlorinated
paraffins (CPs) are high production volume chemicals
and ubiquitous environmental contaminants. CPs are produced and used
as complex mixtures of polychlorinated n-alkanes
containing thousands of isomers, leading to demanding analytical challenges.
Due to their high degree of chlorination, CPs have highly complex
isotopic mass patterns that often overlap, even when applying high
resolution mass spectrometry. This is further complicated in the presence
of degradation products such as chlorinated alkenes (CP-enes). CP-enes
are formed by dehydrochlorination of CPs and are expected thermal
degradation products in some applications of CPs, for example, as
metal working fluids. A mathematical method is presented that allows
deconvolution of the strongly interfered measured isotope clusters
into linear combinations of isotope clusters of CPs and CP-enes. The
analytical method applied was direct liquid injection into an atmospheric
pressure chemical ionization source, followed by quadrupole time-of-flight
mass spectrometry (APCI-qTOF-MS), operated in full scan negative ion
mode. The mathematical deconvolution method was successfully applied
to a thermally aged polychlorinated tridecane formulation (Cl5–Cl9). Deconvolution of mass patterns allowed quantifying fractions of
interfering CPs and CP-enes. After exposure to 220 °C for 2,
4, 8, and 24 h, fractions of CP-enes within the respective interfering
clusters increased from 0–3% at 0 h up to 37–44% after
24 h. It was shown that thermolysis of CPs follows first-order kinetics.
The presented deconvolution method allows CP degradation studies with
mass resolution lower than 20000 and is therefore a good alternative
when higher resolution is not available.
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mass patternspolychlorinated tridecane formulationpressure chemical ionization source24 hdeconvolution methodMass Spectral InterferencesChlorinated Alkenes Chlorinated paraffinsisotope clustersCP degradation studiesThermal Degradation Productsdegradation productsCP-enequadrupole time-of-flight mass spectrometryproduction volume chemicalsresolution mass spectrometry
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