Mass spectrometry analysis of polychlorinated biphenyls: Chemical ionization and selected ion chemical ionization using methane as a reagent gas
In the present paper a quadrupole ion trap mass spectrometer, coupled with a gas chromatograph, was used to compare the electron impact ionization (EI) and chemical ionization (Cl) technique, in terms of their selectivity in polychlorinated biphenyls (PCBs) quantitative analysis. The experi...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Serbian Chemical Society
2000-01-01
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| Series: | Journal of the Serbian Chemical Society |
| Subjects: | |
| Online Access: | http://www.doiserbia.nb.rs/img/doi/0352-5139/2000/0352-51390006431V.pdf |
| Summary: | In the present paper a quadrupole ion trap mass spectrometer, coupled with a
gas chromatograph, was used to compare the electron impact ionization (EI)
and chemical ionization (Cl) technique, in terms of their selectivity in
polychlorinated biphenyls (PCBs) quantitative analysis. The experiments were
carried out with a modified Varian SATURN III quadrupole ion-storage mass
spectrometer equipped with Varian waveform generator, coupled with a gas
chromatograph with DB-5 capillary column. The disadvantage of using EI in
the analysis of PCBs congeners is the extensive fragmentation of the
molecular ion. The main fragmentation pattern recorded in the EI mass
spectra of PCBs was the loss of a chlorine atom from the molecular ion.
Therefore the fragment-ion signal overlapped with the molecular-ion cluster
of lower mass congener. The fragmentation reactions of PCBs are suppressed
if methane is used as a reagent gas for chemical ionization, but fragment
ions are also present in the spectrum as an obstruction for quantitative
analysis. The most selective method for PCBs quantitative analysis appears
to be Cl with mass-selected C2H5 + ions from methane, which results in a
mass spectrum with a negligible amount of fragment ions. |
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| ISSN: | 0352-5139 1820-7421 |