title: Tools to discover anionic and nonionic polyfluorinated alkyl surfactants by liquid chromatography electrospray ionisation mass spectrometry.
abstract: A tiered approach is proposed for the discovery of unknown anionic and nonionic polyfluorinated alkyl surfactants (PFASs) by reversed phase ultra high performance liquid chromatography (UHPLC)--negative electrospray ionisation--quadrupole time of flight mass spectrometry (UHPLC-ESI(-)-QTOF-MS). The chromatographic separation, ionisation and detection of PFASs mixtures, was achieved at high pH (pH=9.7) with NH(4)OH as additive. To distinguish PFASs from other chemicals we used the characteristic negative mass defects of PFASs, their specific losses of 20 Da (HF) and the presence of series of chromatographic peaks, belonging to homologues series with m/z of n×50 Da (CF(2)) or n×100 Da (CF(2)CF(2)). The elemental composition of the precursor ions were deducted from the accurate m/z values of the deprotonated molecules [M-H](-). In case of in-source fragmentation, the presence of dimers, e.g. [M(2)-H](-) and adduct ions such as [M-H+solvent](-) and [(M-H)(M-H+Na)(n)](-) were used to confirm the identity of the precursor ions. In relation to quantification of PFASs, we discuss how their surfactancy influence the ESI processes, challenge their handling in solution and choices of precursor-to-product ions for MSMS of e.g., structural PFAS isomers. The method has been used to discover PFASs in industrial blends and in extracts from food contact materials.
authors.affiliation: University of Copenhagen, The Faculty of Life Sciences, Department of Basic Sciences and Environment, Thorvaldsensvej 40, DK-1871 Frederiksberg, Denmark. xttr@food.dtu.dk
authors.forename: Xenia
authors.initials: X
authors.lastname: Trier
authors.forename: Kit
authors.initials: K
authors.lastname: Granby
authors.forename: Jan H
authors.initials: JH
authors.lastname: Christensen
mesh_terms: D064753:Ammonium Hydroxide; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D018857:Food Packaging; D006845:Hydrocarbons, Fluorinated / Q000032:analysis / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D006878:Hydroxides; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013501:Surface-Active Agents / Q000032:analysis / Q000737:chemistry*; D053719:Tandem Mass Spectrometry; D013696:Temperature
chemical_list: D006845:Hydrocarbons, Fluorinated; D006878:Hydroxides; D013501:Surface-Active Agents; D064753:Ammonium Hydroxide