title: Dichloromethane-enhanced negative ion chemical ionization for the determination of polychlorinated n-alkanes.
abstract: The use of dichloromethane/methane reagent gas mixtures is described as an alternative to conventional electron capture negative ionization for the determination of polychlorinated n-alkanes (PCAs). A nearly exclusive formation of [M + Cl]- adduct ions was observed suppressing the generation of other fragment ions. The resulting enhanced selectivity and sensitivity lowered quantification limits to 3 ng for a technical PCA mixture and 10.5-13.5 pg for single congeners. Response factors for congeners of different degrees of chlorination varied by not more than a factor of 2. Interferences from other polychlorinated compounds present in environmental samples such as toxaphene or chlordanes were suppressed by a factor of 5 or more. The technique was applied for the determination of the composition of technical PCA mixtures as well as for the analysis of PCAs in North Sea dab liver.
authors.affiliation: Organic Analytical Chemistry, University of Basel, Neuhausstrasse 31, 4057 Basel, Switzerland.
authors.forename: Zdenek
authors.initials: Z
authors.lastname: Zencak
authors.forename: Margot
authors.initials: M
authors.lastname: Reth
authors.forename: Michael
authors.initials: M
authors.lastname: Oehme
mesh_terms: D000473:Alkanes / Q000032:analysis*; D000818:Animals; D005432:Flounder; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D006843:Hydrocarbons, Chlorinated / Q000032:analysis*; D008099:Liver / Q000737:chemistry; D008697:Methane / Q000737:chemistry*; D008752:Methylene Chloride / Q000737:chemistry*; D012680:Sensitivity and Specificity
chemical_list: D000473:Alkanes; D006843:Hydrocarbons, Chlorinated; D008752:Methylene Chloride; D008697:Methane