Determination of dioxins/furans and PCBs by quadrupole ion-trap gas chromatography-mass spectrometry

The versatility and sensitivity of the quadrupole ion trap tandem mass spec trometer has been applied to the determination of polychlorodibenzo-p-dioxi ns (PCDDs) and polychlorodibenzofurans (PCDFs), and of polychlorinated biph enyls (PCBs). A brief introduction to the theory of ion confinement in a qu adrupole ion trap permits discussion of ion trajectory stability, mass-sele ctive ion ejection, the frequencies of ion motion, and the role of resonant excitation of ion motion. The tandem mass spectrometric examination of PCD Ds and PCDFs eluting and co-eluting from a gas chromatographic column is de scribed Illustrative examples are given of the analysis of field samples co ntaining PCDDs and PCDFs. A comparison is presented of the performance of e ach of a quadrupole ion trap tandem mass spectrometer, a triple stage quadr upole mass spectrometer and a sector instrument of relatively high mass res olution for the determination of PCDDs and PCDFs. This comparison is made w ith respect to instrument tuning, calibration plots, detection limits, ion signals at low concentration, relative response factors, ionization cross-s ections and the examination of field samples. The application of quadrupole ion trap tandem mass spectrometry to the exam ination of PCBs is focused upon those PCB congeners that have the greatest toxicity. 39 congeners of the total of 209 PCB congeners have been identifi ed as having the greatest toxicities. Chemical ionization has been used for the determination of co-eluting congeners #77 and #110 where the toxicity of the former is much greater than that of the the latter An analytical pro tocol, based on the variation of molecular ion fragmentation according to t he degree (or absence) of chlorine ortho-substitution has been proposed for distinguishing between toxic and nontoxic PCB congeners. (C) 2000 John Wil ey & Sons, Inc.