Methodical approach for the use of GC-TOF MS for screening and confirmation of organic pollutants in environmental water.

The potential of gas chromatography coupled to time-of-flight mass spectrometry (GC-TOF MS) for the screening of organic pollutants in water was explored. After a conventional SPE step with C(18) cartridges, the comparison of spectra with available libraries together with an evaluation of the mass accuracy was the first approach used for the screening and confirmation of target analytes. However, at low analyte concentrations (i.e. below 0.1 microg/l), this procedure was not feasible and the use of the application manager TargetLynx was evaluated. This application allows the selection of up to five representative ions per analyte, measured with high mass accuracy, and their intensity ratio evaluation. Ion selection, extraction mass window and concentration levels were found to be the critical parameters. The reference compound used as 'lock mass' was also found to affect to the quality of information obtained in some particular cases. Full spectral acquisition data generated by the TOF MS analyzer allowed investigation of the presence of several analytes in samples in a post-target style, without the need of reanalyze the water samples.Finally, a methodical approach was established for the reliable screening and confirmation of organic pollutants (PAHs, pesticides, octyl/nonyl phenols) in real-world samples, which led to satisfactory results of approximately 0.1 microg/l.