Gas chromatography and liquid chromatography coupled to mass spectrometry for the determination of fluorotelomer olefins, fluorotelomer alcohols, perfluoroalkyl sulfonamides and sulfonamido-ethanols in water
By J. F. Ayala-Cabrera, E.Moyano, and F.J.Santos
August 27, 2019
In this work, the suitability of gas chromatography-mass spectrometry (GC–MS) and liquid chromatography-tandem mass spectrometry (LC–MS/MS) for the multi-class determination of different families of neutral per- and polyfluoroalkyl substances (PFASs), such as fluorotelomer olefins (FTOs), alcohols (FTOHs) and fluorooctanesulfonamides (FOSAs) and sulfonamido-ethanols (FOSEs), was investigated and compared. Regarding GC–MS, the use of a semi-polar GC column (DB-624, 6%-cyanopropilphenyl 94%-dimethyl polysiloxane) allowed the adequate separation of all the compounds while chemical ionisation (CI) of positive ions as ionisation technique provided the best responses. Concerning UHPLC–MS/MS, atmospheric pressure chemical ionisation (APCI) and photoionisation (APPI) sources allowed the ionisation of all studied neutral PFASs, including FTOs for the first time. High vaporizer temperatures (450 °C) and acetonitrile/water mobile phase mixtures were required to favour the ionisation of FTOs, with adequate ionisation for FTOHs, FOSAs and FOSEs. The chromatographic separation, performed on a totally porous column (Luna C18), allowed the successful separation of the four families of neutral PFASs. After comparing the performance of the studied methods, the highest detectability was achieved using UHPLC–APCI–MS/MS and it was chosen in combination with a solid-phase extraction (SPE) procedure for the analysis of neutral PFASs in water samples. The whole method provided low limits of detection (0.003–6 µg L–1), good precision (RSD < 9%) and trueness (relative error < 10%). The methodology was applied to the analysis of river water samples and the presence of some neutral PFASs were detected (8:2 FTO) and quantified (4:2 FTOH and N-EtFOSA) at low concentration levels (ng L–1).
- Atmospheric pressure chemical ionisation
- Atmospheric pressure photoionisation
- Gas chromatography–mass spectrometry
- Liquid chromatography–tandem mass spectrometry
- Neutral fluorinated compounds
- CI and a semi-polar column provided the best GC–MS conditions for all the compounds.
- Negative-ion APCI provided the lowest LODs for the target compounds by LC–MS.
- For the first time, FTOs were ionised by atmospheric pressure ionisation sources.
- UHPLC–APCI–MS/MS method allowed the multi-class determination of neutral PFASs.
- The presence of neutral PFASs in river waters remains constant through the time.