Environmental screening of acidic compounds based on capillary zone electrophoresis/laser-induced fluorescence detection with identification by gas chromatography/mass spectrometry and gas chromatography/high-resolution massspectrometry

This paper describes the application of capillary zone electrophoresis/lase r-induced fluorescence detection (CZE/LIF) to the discovery of acidic compo unds in environmental matrixes or the screening of extracts for acidic comp onents. Published studies indicate that coal-derived materials contain a si gnificant fraction of acidic compounds relative to materials derived from p etroleum and shales, Such compounds may be useful as marker compounds for s ite assessment and source apportionment issues, and their identification ma y be important in toxicological and other health issues. We used deep-UV li ght from the frequency-doubled Ar ion laser at 244 and 257 nm to study extr acts of samples. The CZE/LIF technique possesses good sensitivity and there fore overcomes one of the limitations of CZE with UV detection. The present work depends on high pressure/temperature solvent extraction of polynuclea r aromatic hydrocarbon (PNA)-contaminated soil, followed by separation usin g CZE, The anionic analytes were separated by using berate or phosphate buf fer (pH 9.2-12.3) after a chemical class separation, Samples were also char acterized by gas chromatography/mass spectrometry (GC/MS) using full scans at low resolution, and elemental compositions were determined unequivocally by GC/high-resolution MS (GC/HRMS) using mass peak profiling (MPP), The si milarity of low-resolution electron ionization mass spectra for a standard, 1-hydroxypyrene, and for a series of compounds in a contaminated-soil extr act suggested that several types of phenolic and hydroxy-PNAs were present, including hydroxylated derivatives of fluorenes, fluoranthenes, and pyrene s, GC/HRMS using MPP confirmed the elemental compositions of the hydroxyflu orenes and hydroxypyrenes (and presumably hydroxyfluouanthenes) as [C13H10O ] and [C16H10O], respectively. A new version of the MPP software was writte n for the Finnigan-MAT 900S-Trap and was similar to that developed previous ly for the VG 250SE, Inclusion of a calibration ion in addition to a lock m ass ion in the multiple-ion detection descriptor provided errors of <1 ppm for the 3 partial profiles of the analytes, A mass resolution of 31 000 was used to resolve the analyte signals from interferences evident in the full M+1 and M+2 profiles in the case of the hydroxyfluorenes, Derivatization w as also performed to form the tert-butyldimethylsilyl derivatives of phenol ic hydroxy groups as a further confirmation of structure.