The chromatographic analysis of 55 environmental markers of CWAs including isomeric andisobaric compounds was accomplished within 20 min, using 1.8 m particle size column. Subsequentidentification of the compounds was achieved by the accurate mass measurement of either protonatedmolecule [M+H]+or ammonium adduct [M+NH4]+and fragment ions. Isomeric and isobaric compoundswere distinguished by chromatographic retention time, characteristic fragment ions generated by bothin-source collision induced dissociation (CID) and CID in the collision cell by MS/MS experiments.