Negative-ion atmospheric pressure ionisation of semi-volatile fluorinated compounds for ultra-high-performance liquid chromatography tandem mass spectrometry analysis

Abstract

In this work, the feasibility of negative-ion atmospheric pressure chemical ionisation (APCI) and atmospheric pressure photoionisation (APPI) for ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) determination of fluorotelomer alcohols (FTOHs), fluorinated octanesulfonamides (FOSAs) and fluorinated octanesulfonamido-ethanols (FOSEs) was evaluated. The study of the effect of mobile phase composition on the atmospheric pressure ionisation of these compounds indicated that methanol/water mixtures provided the best responses in APCI, while acetonitrile/water with a post-column addition of toluene as dopant was the most appropriated mixture in APPI. Under the optimal working conditions, most of the target compounds produced the ion [M-H] as base peak, although in-source collision-induced dissociation fragment ions in APCI and APPI and superoxide adduct ions [M+O] in APPI were also present. These ions proved to be more useful as precursor ions for MS/MS determination than the adduct ions generated in electrospray. Although the UHPLC-APCI-MS/MS method allowed the determination of these semi-volatile compounds at low concentration levels, the analysis by UHPLC-APPI-MS/MS provided the lowest limits of detection and it was applied to the analysis of water samples in combination with solid-phase extraction. Quality parameters demonstrated the good performance of the proposed method, providing low method limits of detection (0.3-6 ng L), good precision (RSD % < 5%) and an accurate quantification (relative error % < 14%). Among the river water samples analysed by the developed method, 4:2 FTOH and N-EtFOSA were determined at 30 and 780 ng L, respectively.

Current progress in the environmental analysis of poly- and perfluoroalkyl substances (PFAS)

“…MS is generally operated in ESI-negative mode due to the fact that most legacy and emerging PFAS are anionic. Although neutral PFAS such as FASAs, FASEs and FTOHs can still be ionized using ESI, atmospheric pressure chemical ionisation (APCI) and atmospheric pressure photoionisation (APPI) have also been tested 16 . LC-MS/MS is as the benchmark analytical technique for PFAS identification in aquatic matrices due to its improved accuracy and precision, great selectivity, and generic applicability, despite its relatively high operational cost and limited sample throughput in comparison to LC-HRMS.…”

“…Up to this day, liquid chromatography (LC) coupled with mass spectrometric (MS) or tandem mass spectrometric (MS/MS) detection is the golden standard for targeted PFAS determination 14 ; Benefiting from the latest improvements in the field of high resolution mass spectrometry (HRMS), novel PFAS have been continuously identified in a variety of environmental matrices 15 . Recently, time-of-flight mass spectrometry (TOF-MS), Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) and orbitrap instrumentations have been utilized for structure proposal of unknown PFAS molecules from more than twenty established classes 16 and contribute to the developing field of emerging PFAS discovery via suspect and non-target screening 17 .…”

“…14 Beneting from the latest improvements in the eld of high resolution Critical Review Environmental Science: Advances mass spectrometry (HRMS), novel PFASs have been continuously identied in a variety of environmental matrices. 15 Recently, time-of-ight mass spectrometry (TOF-MS), Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) and orbitrap instrumentations have been utilized for structure proposal of unknown PFAS molecules from more than twenty established classes 16 and contribute to the developing eld of emerging PFAS discovery via suspect and non-target screening. 17 The objective of the present review was to investigate the newest monitoring trends and the most recent analytical methods for the identication and determination of PFASs in diverse environmental matrices, including untargeted and non-specic approaches.…”

Determination of the dissipative behaviour and final residue of sodium nitrophenol in jujube by liquid chromatography–tandem mass spectrometry

“…With the selected APCI source, methanol was more suitable as the mobile phase than acetonitrile based on the ionization principle of the APCI source (Ayala‐Cabrera et al, 2018). Adding ammonium acetate to the mobile phase led to an increase in the ionization efficiency and sensitivity of the targets, which also contributed to improving the peak shape.…”

Paper spray-atmospheric pressure photoionization-high resolution mass spectrometry for the direct analysis of neutral fluorinated compounds in waterproof impregnation sprays

“…In the GC-MS analysis both electron ionization (EI) and chemical ionization (CI) have been used, although high fragmentation and poor ionization efficiency were reported for some of these compounds. In LC-MS, electrospray ionization (ESI) has been the ionization technique most currently used, although atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI) have also recently been proposed to overcome some of the ionization problems observed in ESI for FTOHs and FOSEs [11]. Concerning AIMS methods, so far none have been reported for these families of neutral PFAS, maybe due to the difficulties for their ionization under electrospray-based mechanisms.…”