Rapid non-target screening of organic pollutants in water by ultraperformance liquid chromatography coupled to time-of-light mass spectrometry

Abstract

We show the potential of ultra-performance liquid chromatography (UPLC) coupled to time-of-flight mass spectrometry (TOF-MS) for screening of non-target organic pollutants in water samples. The great accuracy and the resolution provided by a TOF analyzer allow the mass of any ionizable component in a sample to be accurately measured. Efficient screening applied to environmental samples should ideally detect as many pollutants as possible in one analytical run. This makes necessary the use of powerful chromatographic deconvolution software, which can manage the huge amount of MS data acquired after sample analysis so as to detect components in the sample. It is therefore feasible to compare the experimental data versus a home-made library (empirical and/or theoretical) that can contain hundreds of compounds relevant to the environment. When a compound is not found in the library, its deconvoluted accurate-mass spectra can be used to propose its elemental composition. We apply this strategy to several types of water samples and it has allowed detecting several pesticides (e.g., thiabendazole, imazalil, simazine and diuron) at low ppb levels. We also detected antibiotics (e.g., ofloxacin or ciprofloxacin) and drugs of abuse (e.g., benzoylecgonine, which is a cocaine metabolite). The home-made theoretical library contains more than 500 compounds, including many pesticides and transformation products, antibiotics and several drugs. UPLC-TOF-MS is an efficient technique for the rapid screening of multi-class organic pollutants in water that requires little sample manipulation. Full-acquisition MS data obtained by TOF-MS provide valuable qualitative information, which facilitates safe identification of many different compounds in samples.