A simple and rapid extraction method for sensitive determination of perfluoroalkyl substances in blood serum suitable for exposure evaluation

Investigation of the adsorption/desorption mechanism of perfluoroalkyl substances on HLB-WAX extraction phases for microextraction

The C-F alkyl structural backbone of per- and polyfluoroalkyl substances makes this class of molecules resistant to heat and degradation, leading to their high persistence and mobility in the environment and bioaccumulation in the tissues of living organisms. In this study, 15 PFAS with an alkyl chain length from C₄ to C₁₄, currently monitored by the U.S. Environmental Protection Agency (EPA), were preconcentrated by solid-phase microextraction (SPME) and analyzed by liquid chromatography-tandem mass spectrometry. The adsorption and desorption mechanisms of PFAS onto ion-exchange extraction phases was evaluated to understand the extraction process of PFAS from various environmental matrices under different conditions. This was achieved using two SPME geometries, namely fibers and thin films. The use of thin films resulted in a twofold improvement in extraction efficiency compared to fibers, especially for the short-chain PFAS. Methanol:water (80:20, v/v) was chosen as the optimized desorption solution, with ammonium formate added to minimize carryover. Extraction time profiles for both SPME geometries showed faster equilibration with thin films (30 min) compared to fibers (90-120 min). The linear dynamic range obtained with this method using fibers and thin films ranged from 10 to 5000 ng L^-1 and 2.5-5000 ng L^-1, respectively, with acceptable accuracy (70-130%) and precision (<15%). LOD ranged within 2.5-10 ng L^-1 for fibers and 0.01-0.25 ng L^-1 for thin films. Investigating the factors affecting PFAS recovery in complex samples enabled the quantitative assessment of PFAS contamination in various environmental water samples such as seawater, melted snow and biospecimens like human plasma. A 96-SPME holder was used for validation, which is compatible with sampling in 96-well plates and ensures high throughput in the analysis of real samples. The total concentration of PFAS detected in seawater and snow was 51.3 ng L^-1 and 16.4 ng L^-1, respectively.

Biomonitoring of 89 POPs in blood serum samples of Czech city policemen

In this biomonitoring study, we evaluated the concentrations of 8 polychlorinated biphenyls (PCBs), 11 organochlorinated pesticides (OCPs), 33 brominated flame retardants (BFRs), 7 novel brominated and chlorinated flame retardants (novel FRs) and 30 per- and polyfluoroalkylated substances (PFAS) in human serum samples (n = 274). A total of 89 persistent organic pollutants (POPs) were measured in blood serum samples of city policemen living in three large cities and their adjacent areas (Ostrava, Prague, and Ceske Budejovice) in the Czech Republic. All samples were collected during the year 2019 in two sampling periods (spring and autumn). The identification/quantification of PCBs, OCPs, BFRs, novel FRs and PFAS was performed by means of gas chromatography coupled to (tandem) mass spectrometry (GC-MS/(MS)) and ultra-high performance liquid chromatography coupled to triple quadrupole tandem mass spectrometry (UHPLC-MS/MS). The most frequently detected pollutants were perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluorooctanesulfonate (PFOS), perfluorohexanesulfonate (PFHxS), 2,2',3,4,4',5'-hexachlorobiphenyl (CB 138), 2,2',4,4',5,5'-hexachlorobiphenyl (CB 153), 2,2',3,3',4,4',5-heptachlorobiphenyl (CB 170), 2,2',3,4,4',5,5'-heptachlorobiphenyl (CB 180), hexachlorobenzene (HCB), and p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) quantified in 100% of serum samples. In the serum samples, the concentrations of determined POPs were in the range of 0.108-900 ng g^-1 lipid weight (lw) for PCBs, 0.106-1016 ng g^-1 lw for OCPs, <0.1-618 ng g^-1 lw for FRs and <0.01-18.3 ng mL^-1 for PFAS, respectively. Locality, sampling season, and age were significantly associated with several POP concentrations. One of the important conclusions was that within the spring sampling period, statistically significant higher concentrations of CB 170 and CB 180 were observed in the samples from Ostrava (industrial area) compared to Prague and Ceske Budejovice. Older policemen had higher concentrations of five PCBs and two OCPs in blood serum.

Development and validation of an LC-MS/MS method for the quantitation of 30 legacy and emerging per- and polyfluoroalkyl substances (PFASs) in human plasma, including HFPO-DA, DONA, and cC6O4

Per- and polyfluoroalkyl substances (PFASs) include persistent organic pollutants whose spread is still ubiquitous. Efforts to substitute substances of high concern with fluorinated alternatives, such as HFPO-DA (GenX), DONA (ADONA), and cC6O4, have been made. The aim of this work was to develop and validate an isotopic dilution liquid chromatography-tandem mass spectrometry (LC–MS/MS) method suitable to quantify 30 PFASs in human plasma. Analytes included legacy PFASs (PFOA, PFOS, and PFHxS), fluorinated alternatives (PFBA, PFBS, 6:2 FTSA, HFPO-DA, DONA, and cC6O4), and newly identified compounds (F-53B and PFECHS). The sample preparation was rapid and consisted of simple protein precipitation and centrifugation. Calibration standards and quality control solutions were prepared with a human pooled plasma containing relatively low background levels of the considered analytes. A complete validation was carried out: the lower limits of quantitation (LLOQs) ranged from 0.009 to 0.245 µg/L; suitable linearity (determination coefficients, R² 0.989–0.999), precision (2.0–19.5%, relative standard deviation), and accuracy (87.9–113.1% of theoretical) were obtained for considered concentration ranges. No significant variations of analyte responses were recorded under investigated storage conditions and during matrix effect tests. The external verification confirmed the accuracy of the method, although limited to 12 analytes. The method was also applied to 38 human plasma samples to confirm its applicability. The developed assay is suitable for large-scale analyses of a wide range of legacy and emerging PFASs in human plasma. To our knowledge, this is the first published method including cC6O4 for human biomonitoring.

High throughput analysis of 21 perfluorinated compounds in drinking water, tap water, river water and plant effluent from southern China by supramolecular solvents-based microextraction coupled with HPLC-Orbitrap HRMS

The present work reported a high-throughput strategy for the analysis of 21 perfluorinated compounds (PFCs) in drinking water, tap water, river water and plant effluent from southern China by supramolecular solvent (SUPARS) vortex-mixed microextraction combined with high performance liquid chromatography-Orbitrap high resolution mass spectrometry (HPLC-Orbitrap HRMS). The SUPRAS without heating assistance is less solvent-consumption, meeting the requirements for green environmental protection and sustainable development. Parameters in the microextraction such as volume of dodecanol and tetrahydrofuran (THF), vortexing extraction and centrifugation time, salt concentration were investigated. The optimal extraction conditions were 250 μL of undecanol, 1.0 mL of THF and 20.0% (w/v, 4 g) NaCl. Under the optimum conditions, method limit of detection and method limit of quantitation in the ranges of 0.01-0.08 μg/L and 0.03-0.25 μg/L, good recoveries (72.5-117.8%) and intra-day precision (1.1-11.2%, n = 6), high enrichment factors (48-78) were obtained. The developed method was successfully applied for analysis of PFCs in 13 drinking water, tap water, river water and plant effluent samples collected from southern China. Perfluorobutane sulfonic acid was detected in one river water with concentration of 0.48 μg/L and 1H,1H,2H,2H-Perfluorooctane sulfonic acid was detected in one river water and two plant effluent samples with concentrations in the range of 0.14-0.67 μg/L.

Fluorine and nitrogen functionalized magnetic graphene as a novel adsorbent for extraction of perfluoroalkyl and polyfluoroalkyl substances from water and functional beverages followed by HPLC-Orbitrap HRMS determination

Most of the reported magnetic adsorbents are difficult to absorb multi-class of per- and polyfluoroalkyl substances (PFASs), especially the short-chain PFASs. In this work, a novel fluorine and nitrogen functionalized magnetic graphene (G-NH-FBC/Fe₂O₃) was first synthesized and characterized by scanning electron microscope (SEM), Fourier Transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM). The as-prepared G-NH-FBC/Fe₂O₃ was utilized as adsorbents for the magnetic solid-phase extraction (MSPE) of 19 PFASs from water and functional beverages and showed excellent adsorption capacity probably due to the hydrophobic interaction. Under the optimal pretreatment and instrumental conditions, a selective and sensitive high performance liquid chromatography Orbitrap high resolution mass spectrometry (HPLC-Orbitrap HRMS) method was developed for the determination of PFASs. Results indicated that the proposed method had favorable linearity (R² ≥ 0.994) within a wide range of concentrations. Limit of detection (LOD) and limit of quantification (LOQ) for the developed method ranged from 3 ng/L to 15 ng/L and 10 ng/L to 49 ng/L, respectively. Finally, the method was successfully applied to determine PFASs in drinking water, river water, tap water, factory drainage and functional beverages with recoveries ranging from 71.9% to 117.6% and relative standard deviation of <10%. The prepared G-NH-FBC/Fe₂O₃ was easy to recycle and could be reused for five times without significant decrease in extraction recoveries of PFASs. These results demonstrated that this novel magnetic G-NH-FBC/Fe₂O₃ could efficiently enrich PFASs and the proposed method is reliable and robust for the determination of PFASs in water and beverage samples.

Twenty years of supramolecular solvents in sample preparation for chromatography: achievements and challenges ahead

Supramolecular solvents (SUPRAS) have progressively become a suitable alternative to organic solvents for sample preparation in chromatographic analysis. The inherent properties of these nanostructured solvents (e.g. different polarity microenvironments, multiple binding sites, possibility of tailoring their properties, etc.) offer multiple opportunities for the development of innovative sample treatment platforms not approachable by conventional solvents. In this review, major achievements attained in the combination SUPRAS-chromatography in the last 20 years as well as the challenges that should be addressed in the near future are critically discussed. Among achievements, particular attention is paid to the theoretical and practical knowledge gained that has helped make substantial progress in the area. In this respect, advances in the understanding of the mechanisms involved in SUPRAS formation and SUPRAS-solute interactions driving extractions are discussed, with a view to the setting up of knowledge-based extraction procedures. Likewise, the strategies followed to improve the compatibility of SUPRAS extracts with liquid and gas chromatography and adapt SUPRAS-based extractions to different formats are presented. Ongoing efforts to apply SUPRAS in multicomponent extractions and synthesize tailored SUPRAS for the development of innovative sample treatments are highlighted. Among challenges identified, discussion is focused on the automation of SUPRAS-based sample treatment and the elucidation of SUPRAS nanostructures, which are considered essential for their acceptance in routine labs and the design of tailored SUPRAS with programmed functions. Graphical abstract.

Biological sample preparation: attempts on productivity increasing in bioanalysis

Sample preparation is an important step of any biomedical analysis. Development and validation of fast, reproducible and reliable sample preparation methods would be very helpful in increasing productivity. Except for a few direct injection methods, almost all biological samples should at least be diluted before any analysis. Sometimes dilution is not possible because of the low concentration of the target analyte in the sample, and alternative pretreatments, such as filtration, precipitation and sample clean up using different extraction methods, are needed. This review focuses on the recent achievements in the pretreatment of biological samples and investigates them in six categories (i.e., dilution, filtration/dialysis, precipitation, extraction [solid-phase extraction, liquid–liquid extraction], novel techniques [turbulent flow chromatography, immunoaffinity method, electromembrane extraction] and combined methods). Each category will be discussed according to its productivity rate and suitability for routine analysis, and the discussed methods will be compared according to the mentioned indices.

Fast determination of perfluorocompounds in packaging by focused ultrasound solid-liquid extraction and liquid chromatography coupled to quadrupole-time of flight mass spectrometry

A focused ultrasound solid-liquid extraction (FUSLE) and liquid chromatography (HPLC) coupled to quadrupole-time of flight mass spectrometry (QTOF-MS/MS) based method is proposed to determine six perfluorocarboxylic acids (PFCA) and perfluorooctane sulfonate (PFOS) in food-contact packaging. FUSLE, a simple, inexpensive and fast extraction technique, has been carried out with just 8mL of ethanol in one cycle of only 10s. The whole method presented good repeatability and intermediate precision, with RSDs below 11% and 15%, respectively; limits of detection, with values between 0.5ng/g and 2.2ng/g, and successful recovery values, around 100% in all cases. The developed method has been validated and applied to the analysis of real food-contact packaging samples. FUSLE results have been compared to those obtained with pressurized liquid extraction (PLE) and no significant differences between them have been found. PFAA were detected in all the packaging samples analyzed, in a concentration range between 4ng/g and 29ng/g, being PFHpA (perfluoroheptanoic acid) the most abundant of them.