Fast and sensitive determination of per- and polyfluoroalkyl substances in seawater.

In this work, a novel, fast, and sensitive method was developed for perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS) and PFOS precursor's determination in seawater. The proposed method consists in a vortex-assisted liquid-liquid microextraction (VALLME) combined with liquid chromatography (LC) and LTQ-Orbitrap high resolution mass spectrometry (LTQ-Orbitrap HRMS) determination. Several parameters affecting both the HPLC-LTQ Orbitrap HRMS determination and the VALLME were studied, with special attention to blank contamination problem. The use of LTQ-Orbitrap-HRMS in full mode, quantifying the target analytes using the exact mass, provides a very powerful detection in terms of sensitivity and specificity maintaining all the information provided by the full mass spectra, allowing, also, the identification of non-target substances. The use of matrix-matched calibration, together with labelled surrogate standards, minimize matrix effects and compensate potential recovery losses, resulting in recoveries between 95 and 105%, with excellent sensitivity (quantitation limit between 0.7 and 6 ng L-1) and precision (4-10%). The proposed method requires only 35 mL of sample and 100 µL of extracting solvent, is fast and avoids the use of other solvents to obtain the dispersive cloudy solution, simplifying the procedure and improving the existing procedures for the determination of per- and polyfluoroalkyl substances (PFASs) in seawater in terms of green analytical chemistry. The method was successfully validated by participating in a proficiency test assay provided by the National Measurement Institute of the Australian Government for the determination of PFOA, total PFOS and linear PFOS in waters. A revision of the state of the art in the last twelve years of methods for the analysis of PFASs in seawater and other types of water was performed, and a critical comparison between the developed method and the previously published was included. Finally, the method was applied to the analysis of samples from Ría de Vigo, a sensitive and semiconfined coastal area located in the northwest of Spain. PFOS, N-methyl perfluorooctanesulfonamide (n-MeFOSA) and N-ethyl perfluorooctanesulfonamide (n-EtFOSA) were detected in samples at levels lower than the maximum allowable concentration (MAC) established by Directive 2013/39/EU, but above the annual average (AA) levels.

Liquid chromatographic methods to analyze hindered amines light stabilizers (HALS) levels to improve safety in polyolefins.

A chromatographic method using ultra performance LC with ultraviolet spectrophotometry detection system (UPLC-UV-visible (UV/Vis)) (UPLC, ultra performance LC) was developed to determine Chimassorb 944 and Tinuvin 770, high- and low-molecular mass hindered amine light stabilizers, respectively. The use of a bridge ethylene hybrid-based particles C(18) UPLC column, being compatible with a buffered mobile phase adjusted to pH 11.5, was used to achieve a satisfactory elution of possible non-ionizated units of polymeric Chimassorb 944. In addition, a HPLC with positive ion mode ESI and hybrid linear ion trap (LTQ) Fourier transform (FT) Orbitrap MS detection system (HPLC-UV/Vis-ESI-LTQ(FT)Orbitrap) was used for screening and identification purposes. Reliable determinations of monomeric units of Chimassorb 944 and molecule of Tinuvin 770 were achieved by HPLC-ESI(+)-LTQ FT Orbitrap MS method using scan mode. Quality parameters of UPLC-UV/Vis method were evaluated. Obtained LODs and LOQs were 3.41 and 11.4 mg/L for Tinuvin 770 and 0.83 and 2.78 mg/L for Chimassorb 944, respectively. Satisfactory quality parameters of this chromatography method provided the chance to count on a good tool to know the compliance with legal requirements.