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Updated: Sep 20, 2026

Analysis of Complex Molecules and Their Reactions on Surfaces by Means of Cluster-Induced Desorption/Ionization Mass Spectrometry
Published on: March 1, 2020
Dichloromethane-enhanced negative ion chemical ionization for the determination of polychlorinated n-alkanes
Zdenek Zencak1, Margot Reth, Michael Oehme
1Organic Analytical Chemistry, University of Basel, Neuhausstrasse 31, 4057 Basel, Switzerland.
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.
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