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 atmosphe ric pressure chemical ionization mass spectrometry (APCI-MS), via a he ated pneumatic nebulizer interface, for the determination of the polyc yclic aromatic sulfur heterocycle (PASH) content of samples obtained b y the fractionation of an extract of a pond sediment contaminated by c oke-oven residues. Some of the samples produced by the fractionation p rocedure contained large amounts of other polycyclic aromatic compound s (PACs) which co-eluted with the compounds of interest, making it dif ficult 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 co mplex matrices, was investigated. Initially, PASH standards were injec ted into the mass spectrometric system by flow injection and their col lisionally induced dissociation mass spectra recorded From these resul ts, it was possible to select ions suitable for selected reaction moni toring (SRM) experiments on both the PASH standards (to establish dete ction 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 fr actions. 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. Qu antification of the PASH standards by RPLC-SRM in the extracts found t hem to be present at high levels.