title: Differentiation of (Mixed) Halogenated Dibenzo-p-Dioxins by Negative Ion Atmospheric Pressure Chemical Ionization.
abstract: Brominated and mixed halogenated dibenzo-p-dioxins (PBDDs and PXDDs) may well be as toxic as 2,3,7,8-tetrachloro-dibenzo-p-dioxin (2378-TCDD), a compound reputed as one of the most toxic chemicals known to exist. However, studies on the occurrence of PXDDs have been hampered by a lack of authentic standards as well as separation techniques capable of resolving the enormous number of potential isomers. Electron ionization (EI) mass spectrometry based methods are of limited value due to the lack of isomer specific fragmentation. Negative ion atmospheric pressure chemical ionization (APCI(-)) of 2378-TCDD was described in this journal over 30 years ago. Under these conditions, the reaction between O2(-•) and 2378-TCDD results in structure diagnostic cleavages of the C-O bonds, which can distinguish TCDD isomers on the basis of Cl distribution between the two aromatic rings. In the present study, the analogous ether cleavages of PBDDs and PXDDs were studied using a gas chromatograph-quadrupole time-of-flight (GC-QTOF) mass spectrometer coupled using APCI. The results indicate comparable detection limits for the radical cations [M(•+)] and negative pseudomolecular ions [M-Cl+O](-): approximately 5 fg and 10 fg, respectively, for 2378-TCDD and 5-10 fg and 10-30 fg, respectively, for the 2,3,7,8-substituted PXDDs. Detection limits obtained by monitoring the ether cleavage products were somewhat higher (between 100 and 600 fg) but still acceptable for trace analysis of PXDDs. Such reactions may resolve coeluting isomers, which is crucial for the identification of PXDDs. The technique is demonstrated by differentiating PXDD isomer classes in a sample obtained from a major industrial fire that would not be feasible using EI or positive ion APCI(+).
authors.affiliation: McMaster University , 1280 Main Street West, Hamilton, Ontario L8S 4M1, Canada.
authors.forename: Sujan
authors.initials: S
authors.lastname: Fernando
authors.affiliation: McMaster University , 1280 Main Street West, Hamilton, Ontario L8S 4M1, Canada.
authors.forename: M Kirk
authors.initials: MK
authors.lastname: Green
authors.affiliation: Penn State University , 107 Althouse Laboratories, University Park, Pennsylvania 16802, United States.
authors.forename: Kari
authors.initials: K
authors.lastname: Organtini
authors.affiliation: Penn State University , 107 Althouse Laboratories, University Park, Pennsylvania 16802, United States.
authors.forename: Frank
authors.initials: F
authors.lastname: Dorman
authors.affiliation: Waters Corporation , Altrincham Road, Wilmslow SK9 4AX, U.K.
authors.forename: Rhys
authors.initials: R
authors.lastname: Jones
authors.affiliation: Ministry of the Environment and Climate Change , 125 Resources Road, Toronto, Ontario M9P 3V6, Canada.|University of Toronto , 80 St. George Street, Toronto, Ontario M5S 3H6, Canada.
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Reiner
authors.affiliation: McMaster University , 1280 Main Street West, Hamilton, Ontario L8S 4M1, Canada.|Ministry of the Environment and Climate Change , 125 Resources Road, Toronto, Ontario M9P 3V6, Canada.
authors.forename: Karl J
authors.initials: KJ
authors.lastname: Jobst
mesh_terms: D001274:Atmospheric Pressure; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D057230:Limit of Detection; D015394:Molecular Structure; D000072317:Polychlorinated Dibenzodioxins / Q000032:analysis*; D013481:Superoxides / Q000737:chemistry
chemical_list: D000072317:Polychlorinated Dibenzodioxins; D013481:Superoxides