Capillary gas chromatographic introduction of environmental compounds into a trochoidal electron monochromator/mass...

A gas chromatograph was interfaced to an electron monochromator/quadrupole mass spectrometer. The new system was tested for the analysis of environmental compounds. Detection sensitivity for hexachlorobenzene (HCB) through the gas chromatograph was 5 pg or better, and a mass-resolved molecular ion cluster for this compound on the fly was achieved with 10.8 ng of sample. An ion chromatogram was obtained using 45 ng of Aroclor 1254, and the extract from a trout muscle sample recently collected in the Arctic yielded a chromatographic profile similar to that observed using negative ion chemical ionization mass spectrometry. A mixture of HCB and 2,4,6-trinitrotoluene (TNT) were shown to be distinguishable at 2.4-eV electron energy. The energetics of regioselective fragmentation of [4-15NO2]TNT by dissociative electron capture can be determined on the fly. Complete negative ion gas chromatography/mass spectrometry (GC/MS) spectra were obtained for hexafluorobenzene and TNT by simultaneously ramping the electron energy from -2 to 15 eV and scanning the mass over a 200-Da range.