APPLICATION OF REVERSED-PHASE LIQUID-CHROMATOGRAPHY WITH ATMOSPHERIC-PRESSURE CHEMICAL-IONIZATION TANDEM MASS-SPECTROMETRY TO THE DETERMINATION OF POLYCYCLIC AROMATIC SULFUR HETEROCYCLES IN ENVIRONMENTAL-SAMPLES

Reversed-phase liquid chromatography (RPLC) was combined with atmospheric pressure chemical ionization mass spectrometry (APCI-MS), via a heated pneumatic nebulizer interface, for the determination of the polycyclic aromatic sulfur heterocycle (PASH) content of samples obtained by the fractionation of an extract of a pond sediment contaminated by coke-oven residues. Some of the samples produced by the fractionation procedure contained large amounts of other polycyclic aromatic compounds (PACs) which co-eluted with the compounds of interest, making it difficult to obtain mass spectra suitable for compound identification and verification. Therefore, the use of tandem mass spectrometry (MS/MS), as a selective method for the identification of target analytes in complex matrices, was investigated. Initially, PASH standards were injected into the mass spectrometric system by flow injection and their collisionally induced dissociation mass spectra recorded From these results, it was possible to select ions suitable for selected reaction monitoring (SRM) experiments on both the PASH standards (to establish detection limits and also retention times which could be used to identify these compounds) and the fractions (to establish the possible presence of the selected PASHs in the fractions). The RPLC-SRM experiments led to a tentative identification of some of the PASH standards in the fractions. However, the use of multiple reaction monitoring experiments allowed the positive identification of dibenzothiophene, phenanthro[4,5-bcd] thiophene, phenanthro [3,4-b] thiophene and benzo[b]naphtho[2,3-d]thiophene in the fractions, along with several of their isomers. Quantification of the PASH standards by RPLC-SRM in the extracts found them to be present at high levels.