Determination of polychlorinated biphenyls by chemical ionization mass spectrometry

Analysis of polychlorinated biphenyls by quadrupole ion trap mass spectrometry: Part I - Chemical ionization studies of co-eluting congeners 77 and 110

“…[8][9][10][11][12][13] There have been two basic approaches to solving this problem: i) development of preparative techniques to separate non-ortho from ortho-substituted PCBs prior to HRGC analysis, and ii) development of instrumental techniques based on GC detectors that are more selective than the ECD.…”

“…The main fragmentation pattern recorded in electron impact mass spectra of all PCBs is loss of one or more chlorine atoms from the molecular ion. [11][12][13] Thus, even when co-eluting congeners of different molecular mass are to be distinguished, chlorine loss of the higher mass congener may cause a major interference in the determination of the lower mass congener. The selected ion monitoring (SIM) mass spectrometric technique is acceptable for quantitative analysis only when an ion of interest does not overlap with an interfering ion.…”

“…18 Chemical ionization mass spectrometry (CIMS) has been used in selected positive ion monitoring mode for analysis of various hazardous compounds, 20,21 including PCB congeners in environmental samples. 12,13 In comparison to HRGC-ECD, this technique suffers from decreased molecular sensitivity with increasing molar weight, as the ionization efficiency is not dependent on molar chlorine content. Quantitative data obtained by ECD and CIMS positive ion monitoring techniques are comparable in terms of sensitivity only for PCB congeners containing three, four or five chlorine atoms.…”

“…Quantitative data obtained by ECD and CIMS positive ion monitoring techniques are comparable in terms of sensitivity only for PCB congeners containing three, four or five chlorine atoms. 12 The mass spectra produced by CIMS indicate that there are contributions from charge exchange (EI-like mass spectra) superimposed on the CI mass spectrum, where the protonated molecule is the dominant feature. 22 Preliminary experiments with congener 77 showed almost exact duplication of each peak in the chlorine isotope molecular cluster in a methane positive ion CI mass spectrum of this congener.…”

Determination of byproduct polychlorobiphenyls in commercial products and wastes by high-resolution gas chromatography/electron impact mass spectrometry

“…The response factors are relatively consistent among isomers of a given degree of chlorination (11,19), making possible the selection of a single congener for calibration for each homologue. The use of positive chemical ionization (11,20) and negative chemical ionization (11,17,21) has also been applied to PCB analysis. Negative chemical ionization has the distinct advantage of sensitivity for the more highly chlorinated homologues (17,21).…”