Ion-molecule reactions of halocarbon cations with polycyclic aromatic hydrocarbons in a quadrupole ion trap - Part II - Applications to environmental analysis

Ion-molecule reactions between the cations CH3CHF+ and CH3CF2+ generated from 1,1-difluoroethane and gas chromatographic eluents from a sediment extract containing polycyclic aromatic hydrocarbons (PAHs) were used to differentiate goups of PAH structural isomers, Formation of specific adducts led to characteristic mass spectra for the different isomers. Differences in the ion chromatograms for M+, MH+, [M+CH3CHF](+), [M +CH3CHF-HF](+), [M+CH(3)CF2](+) and [M+CH3CF2-HF](+) (M=PAH molecule) allowed the resolution of co-eluting isomers. As the ratio of yields of adducts was not changed by methyl substitution, it was possible to differentiate and quantitate alkylated PAHs for which standards were not available, By performing a series of transformations between the ion chromatograms of the most characteristic;adducts, information on individual isomer groups could he deconvoluted from complex clusters of isomers. This ion trap/chemical ionization technique displayed calibration curse parameters similar to those for electron ionization analysis and limits of detection of 170 pg in the sediment extract. (C) 1998 John Wiley & Sons, Ltd.