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+ generat ed from 1,1-difluoroethane and gas chromatographic eluents from a sedi ment extract containing polycyclic aromatic hydrocarbons (PAHs) were u sed to differentiate goups of PAH structural isomers, Formation of spe cific adducts led to characteristic mass spectra for the different iso mers. Differences in the ion chromatograms for M+, MH+, [M+CH3CHF](+), [M +CH3CHF-HF](+), [M+CH(3)CF2](+) and [M+CH3CF2-HF](+) (M=PAH molecu le) allowed the resolution of co-eluting isomers. As the ratio of yiel ds of adducts was not changed by methyl substitution, it was possible to differentiate and quantitate alkylated PAHs for which standards wer e 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 o f isomers. This ion trap/chemical ionization technique displayed calib ration curse parameters similar to those for electron ionization analy sis and limits of detection of 170 pg in the sediment extract. (C) 199 8 John Wiley & Sons, Ltd.