Stability of fluorinated surfactants in advanced oxidation processes—A follow up of degradation products using flow injection–mass spectrometry, liquid chromatography–mass spectrometry and liquid chromatography–multiple stage mass spectrometry

The advanced oxidation process (AOP) reagents ozone (O3), O3/UV, O3/H2O2, and H2O2/Fe2+ (Fentonʹs reagent) were applied to the anionic and the non-ionic fluorinated surfactants perfluorooctanesulfonate (PFOS) and N-ethyl-N-(perfluoroalkyl)-sulfonyl-glycinic acid (HFOSA-glycinic acid) or N-ethyl-N-perfluoroalkyl sulfonylamido-2-ethanol polyethoxylates (NEtFASE-PEG), their methyl ethers (NEtFASE-PEG methyl ether) and partly fluorinated alkyl-ethoxylates (FAEO) dissolved in ultrapure water. To monitor the efficiencies of destruction samples were taken during the treatment period of 120 min. After sample concentration by C18-solid phase extraction (SPE) and desorption MS, coupled with atmospheric pressure chemical ionisation (APCI) or electrospray interface (ESI) was applied for detection. No elimination of PFOS was observed while HFOSA-glycinic acid and AOP treated non-ionic surfactants were eliminated by oxidation. Degradation products could be detected and identified. So PFOS was observed during HFOSA-glycinic acid oxidation. Polyethylene glycols (PEG) and PEG methyl ethers were generated from non-ionic fluorinated surfactants beside their oxidation products – aldehydes and acids – all identified by tandem (MS–MS) or multiple stage mass spectrometry (MSn). AOP treatment of FAEO blend resulted in a mixture of partly fluorinated alcohols, separated and identified using GC–MS.