Isomeric characterization of polychlorinated biphenyls using gas chromatography-Fourier transform infrared/gas chromatography-mass spectrometry

An instrument combining the capabilities of both Fourier transform infra-red spectroscopy (FTIR) and mass spectrometry (MS) to analyse simultaneously the various components in PCB mixtures, as separated by capillary column gas chromatography (GC), was discussed. The sensitivity of vibrational spectroscopy to subtle differences in structure was highly complementary to GC-MS for qualitative identification of individual PCB isomers and congeners. The infrared apparatus had the facility for low-temperature trapping (77K) of GC effluent prior to analysis. The infrared spectra produced resembled normal room-temperature condensed-phase spectra and led to lower detection limits (500 pg for 3,3',4,5-tetrachlorobiphenyl). The GC-MS portion of the instrument improved quantitative capabilities, with sub-pg limits possible using selective ion monitoring.