Itsaso Zabaleta

Focused ultrasound solid–liquid extraction for the determination of perfluorinated compounds in fish, vegetables and amended soil

In the present work a method was developed for the determination of different perfluorinated compounds (PFCs), including three perfluorinated sulfonic acids (PFSAs), seven perfluorocarboxylic acids (PFCAs), three perfluorophosphonic acids (PFPAs) and perfluorooctanesulfonamide (PFOSA) in fish, vegetables and amended soil samples based on focused ultrasound solid-liquid extraction (FUSLE) followed by solid-phase extraction (SPE) clean-up and liquid chromatography-tandem mass spectrometry (LC-MS/MS). Different variables affecting the chromatographic separation (column type and pH of the mobile phase), the electrospray ionization (capillary voltage, nebulizer pressure and drying gas flow) and mass spectrometric detection (fragmentor voltage and collision energy) were optimized in order to improve the sensitivity of the separation and detection steps. In the case of FUSLE variables such as the solvent type, the solvent volume, the extraction temperature, the sonication and extraction time and the percentage of applied irradiation power were studied. Under optimized conditions, sonication of 2.5min with pulse times on of 0.8s and pulse times off of 0.2s in 7mL of (9:1) acetonitrile (ACN): water mixture in duplicate guaranteed exhaustive extraction of the matrices analyzed. Due to the non-selective extraction using FUSLE, different SPE cartridges (200-mg Waters Oasis-HLB, 150-mg Waters Oasis-WAX and 150-mg Waters Oasis-MAX) were tested in terms of extraction efficiency and matrix effect both in the extraction and detection steps. Mix mode SPE using Waters Oasis-WAX provided the best extraction efficiencies with the lowest matrix effect. The final method was validated in terms of recovery at two fortification levels (in the 80-120% for most of the analytes and matrices), precision (relative standard deviation in the 2-15% range) and method detection limits (MDLs, 0.3-12.4ng/g for vegetables, 0.2-12.5ng/g for fish and 1-22ng/g for amended soil). Finally the method was applied for the determination of the 14 PFCs in different vegetables and fish samples from a local supermarket and in a soil amended with a compost from a local wastewater treatment plant (WWTP).

Simultaneous determination of perfluorinated compounds and their potential precursors in mussel tissue and fish muscle tissue and liver samples by liquid chromatography-electrospray-tandem mass spectrometry.

An analytical method for the simultaneous determination in fish liver and muscle tissue and mussel samples of 14 perfluorinated compounds (PFCs), including three perfluoroalkylsulfonates (PFSAs), seven perfluorocarboxylic acids (PFCAs), three perfluorophosphonic acids (PFPAs) and perfluorooctanesulfonamide (PFOSA), and 10 potential precursors, including four polyfluoroalkyl phosphates (PAPs), four fluorotelomer saturated acids (FTCAs) and two fluorotelomer unsaturated acids (FTUCAs), was developed in the present work. Different clean-up strategies by means of solid-phase extraction (SPE) using a mix-mode weak anion exchanger (WAX), reverse phase Envi-Carb or a combination of them was optimized and evaluated for the clean-up of focused ultrasonic solid-liquid (FUSLE) extracts before the analysis by liquid chromatography-triple quadrupole tandem mass spectrometry (LC-MS/MS). Mix-mode WAX coupled in-line to Envi-Carb was finally selected since it rendered the cleanest extracts and minimum matrix effect. The FUSLE-SPE-LC-MS/MS methodology was validated in terms of recovery, precision and method detection limits (MDLs). Apparent recovery values in the 65-116%, 59-119% and 67-126% range and MDLs in the 0.1-2.7 ng/g, 0.1-3.8 ng/g and 0.2-3.1ng/g range were obtained for liver, mussel and fish muscle tissue samples, respectively. The method developed was applied to the analysis of grey mullet liver (Chelon labrosus) and mussel (Mytilus galloprovincialis) samples from the Basque Coast (North of Spain) and Yellowfin tuna muscle tissue (Thunnus albacares) samples from the Indian Ocean. To the best of our knowledge this is the first method that describes the simultaneous determination of 14 PFCs and 10 potential precursors in fish liver, fish muscle tissue and mussel samples. Besides, this is the first time that 8:2 monosubstituted polyfluorodecyl phosphate (8:2 monoPAP) and 8:2 disubstituted polyfluorodecyl phosphate (8:2 diPAP) were detected in mussel and tuna samples, respectively.

Uptake of perfluorooctanoic acid, perfluorooctane sulfonate and perfluorooctane sulfonamide by carrot and lettuce from compost amended soil.

Sewage sludge, which acts like a sink for many pollutants, including metals, pathogens and organic pollutants, that are not completely removed in waste water treatment plants (WWTPs), is applied as a nutrient rich organic fertilizer in many agricultural applications. In the present work, carrot and lettuce crops were grown in two different compost amended soils fortified with perfluorooctanoic acid (PFOA), perfluorosulfonate acid (PFOS) and perfluorosulfonamide (FOSA) and cultivated in a greenhouse. The plants were harvested and divided into root core, root peel and leaves in the case of carrots and into heart and leaves for lettuces. Concentrations for all the different compartments were determined to assess the bioconcentration factors (BCFs) and the plant distribution of the target analytes. The highest carrot BCFs for PFOA and PFOS were determined in the leaves (0.6-3.4), while lower values were calculated in the core (0.05-0.6) and the peel (0.05-1.9) compartments. However, PFOA was taken up in the translocation stream and accumulated more than PFOS in the edible part of lettuce. FOSA was totally degraded in the presence of carrot; however, a lower FOSA degradation was observed in presence of the lettuce, which was dependent on the total organic carbon (TOC) content of the soil. The higher the TOC value, the higher the FOSA degradation observed. No degradation was observed in the crop absence. In the case of the carrot experiments, different polymeric materials (polyethersulfone, PES, polyoxymethylene, and silicone rod) were tested to predict the concentration in the cultivation media. A high correlation (r(2)>0.63) was observed for the BCFs in the PES and in the carrot core and peel for PFOA and PFOS. It could be, concluded that the PES can be used as a first approach for the determination of the uptake of compounds such as PFOS and PFOA in carrot.

Fast and simple determination of perfluorinated compounds and their potential precursors in different packaging materials.

A simple and fast analytical method for the determination of fourteen perfluorinated compounds (PFCs), including three perfluoroalkylsulfonates (PFSAs), seven perfluorocarboxylic acids (PFCAs), three perfluorophosphonic acids (PFPAs) and perfluorooctanesulfonamide (PFOSA) and ten potential precursors, including four polyfluoroalkyl phosphates (PAPs), four fluorotelomer saturated acids (FTCAs) and two fluorotelomer unsaturated acids (FTUCAs) in different packaging materials was developed in the present work. In order to achieve this objective the optimization of an ultrasonic probe-assisted extraction (UPAE) method was carried out before the analysis of the target compounds by liquid-chromatography-triple quadrupole-tandem mass spectrometry (LC-QqQ-MS/MS). 7 mL of 1 % acetic acid in methanol and a 2.5-min single extraction cycle were sufficient for the extraction of all the target analytes. The optimized analytical method was validated in terms of recovery, precision and method detection limits (MDLs). Apparent recovery values after correction with the corresponding labeled standard were in the 69-103 % and 62-98 % range for samples fortified at 25 ng/g and 50 ng/g concentration levels, respectively and MDL values in the 0.6-2.2 ng/g range were obtained. The developed method was applied to the analysis of plastic (milk bottle, muffin cup, pre-cooked food wrapper and cup of coffee) and cardboard materials (microwave popcorn bag, greaseproof paper for French fries, cardboard box for pizza and cinema cardboard box for popcorn). To the best of our knowledge, this is the first method that describes the determination of fourteen PFCs and ten potential precursors in packaging materials. Moreover, 6:2 FTCA, 6:2 FTUCA and 5:3 FTCA analytes were detected for the first time in microwave popcorn bags.

Focused ultrasound assisted extraction for the determination of PBDEs in vegetables and amended soil.

Focused-ultrasound solid-liquid extraction was developed for the extraction of polybrominated diphenyl ethers in vegetables and amended soil. Firstly, solid-phase extraction clean-up using 2g and 5 g of Florisil and 2-g silica cartridges were evaluated and elution profile was also optimised. Similar recoveries were obtained for most compounds while better recoveries were obtained for 5-g Florisil in the case of the heavier PBDEs. FUSLE extraction time (2 min) guaranteed quantitative extraction of the target analytes in the four studied matrices (69-130%). Method detection limit values were in the range of 1-5 ng g(-1) for splitless injection in a gas chromatograph coupled to a mass spectrometer and no significant improvement was obtained for large volume injection. Relative standard deviation values were between 1% and 30%. Recoveries obtained using FUSLE were compared with those obtained with microwave assisted extraction and the developed method was also applied to a certify reference material of polybrominated diphenyl ethers and polychlorinared biphenyls in sediment. Similar values were obtained in the case of carrot and pepper matrices (77-130% for FUSLE and 77-112% for MAE). However, MAE provided extraction recoveries higher than 100% for most of the BDE congeners in lettuce and amended soil.

Biodegradation and Uptake of the Pesticide Sulfluramid in a Soil–Carrot Mesocosm

N-ethyl perfluorooctane sulfonamide (EtFOSA) is the active ingredient of Sulfluramid, a pesticide which is used extensively in South America for control of leaf-cutting ants. Despite being a known precursor to perfluorooctanesulfonate (PFOS), the importance of EtFOSA as a source of environmental PFOS remains unclear. In the present work, uptake, leaching, and biodegradation of EtFOSA and its transformation products were assessed over 81 days in soil-carrot ( Daucus carota ssp sativus) mesocosms for the first time. Experiments performed in the presence of carrot produced PFOS yields of up to 34% using a technical EtFOSA standard and up to 277% using Grão Forte, a commercial Sulfluramid bait formulation containing 0.0024% EtFOSA. Perfluorooctane sulfonamido acetate (FOSAA), perfluorooctane sulfonamide (FOSA), and perfluorooctanoic acid (PFOA) also formed over the course of the experiments, with the latter substance attributed to the presence of perfluorooctanamide impurities. The leachate contained low levels of transformation products and a high FOSA:PFOS ratio, consistent with recent observations in Brazilian surface water. In carrots, the more hydrophilic transformation products (e.g., PFOS) occurred primarily in the leaves, while the more hydrophobic products (e.g., FOSA, FOSAA, and EtFOSA) occurred in the peel and core. Remarkably, isomer-specific analysis revealed that the linear EtFOSA isomer biodegraded significantly faster than branched isomers. These data collectively show that the application of Sulfluramid baits can lead to the occurrence of PFOS in crops and in the surrounding environment, in considerably higher yields than previously thought.

Enrichment of perfluorinated alkyl substances on polyethersulfone using 1-methylpyperidine as ion-pair reagent for the clean-up of carrot and amended soil extracts.

The development of a simple, cheap and environment friendly analytical method for the simultaneous determination of different perfluoroalkyl substances (PFASs) including seven perfluoroalkyl carboxylic acids, three perfluoroalkane sulfonic acids and perfluorooctanesulfonamide in carrot and amended soil was carried out in the present work. The method was based on focused ultrasound solid-liquid extraction followed by extract clean-up through enrichment of the target compounds on a polymeric material using an ion-pair reagent and detection by liquid chromatography-tandem mass spectrometry. The following variables affecting the clean-up step were evaluated: the nature of the polymeric material (polyethersulfone, PES, versus silicone rod), the amount of the polymeric material (from 1 to 9 mg), the ion-pair reagent (1-methylpyperidine, 1-MP, versus tetrabutylammonium salts), the concentration of the ion-pair reagent (from 5 to 50 mM) and the extraction time (from 15 min to 24 h). Optimum clean-up conditions were obtained using preconcentration on 9 mg of PES polymeric material combined with 5 mM 1-MP as ion-pair reagent for 3h. The method was validated in terms of apparent recoveries in the range of 77-140% and 95-137% at the low concentration (50 ng g(-1)) and in the range of 70-136% and 79-132% at the high concentration (290 ng g(-1)) for amended soil and carrot, respectively, after correction with the corresponding labeled standards. Precision, as relative standard deviation, was within 2-23%, while method detection limits were 0.31-2.85 ng g(-1) for amended soil and 0.11-1.83 ng g(-1) for carrot. In the absence of a certified reference material for the target analytes in the matrices studied, inter-method comparison was carried out and the same samples were processed using two independent clean-up procedures, the one developed in the present work and a classical based on solid-phase extraction. Statistically comparable results were obtained according to the one-way analysis of variance for peel, core, leaves as well as amended soil (F(Calc)=2.59, 5.06, 5.82 and 2.34 <F(Crit)=7.71). Finally, the method was applied for the determination of PFASs in uptake experiments where carrots were cultivated in an amended soil polluted with perfluorooctane sulfonic acid (PFOS) at 500 ng g(-1) level. The highest concentration was measured in the carrot leaves (669 ng g(-1)), while the concentrations in peel and core were at the same level (72 ng g(-1) and 62 ng g(-1) respectively), concluding that translocation of PFOS from the soil to the leaves had occurred.

Screening and identification of per- and polyfluoroalkyl substances in microwave popcorn bags

Liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (LC-QToF-MS) was used for the accurate identification (<10ppm) of different polyfluoroalkylphosphates (PAPs) and their intermediate and end degradation products in popcorn bags. Up to 46 per- and polyfluoroalkyl substances (PFASs) and precursors were identified. Moreover, an accurate method based on focused ultrasonic solid-liquid extraction (FUSLE) and a clean-up step with Envi-Carb sorbent was validated and applied to the quantification of 24 PFASs in popcorn bags from over twelve European countries, three American countries and two Asian countries. To the best of our knowledge, this is the first time that identification and quantification of some intermediates of PFAS precursors (different chain length fluorotelomer saturated acids (FTCAs) and fluorotelomer unsaturated acids (FTUCAs)) have been reported. Moreover, different patterns in the microwave popcorn bag composition were observed within the countries; while in European and American countries short chain PFASs were detected, Asian countries still use long chain PFASs.

Sulfluramid use in Brazilian agriculture: A source of per- and polyfluoroalkyl substances (PFASs) to the environment

N-Ethyl perfluorooctane sulfonamide (EtFOSA) is a perfluorooctane sulfonate (PFOS) precursor and the active ingredient in sulfluramid, a pesticide which is used extensively in Brazil for management of leaf cutting ants. Here we investigate the occurrence of EtFOSA, PFOS, and other per- and polyfluoroalkyl substances (PFASs) in soil, eucalyptus leaves, water (ground, riverine, and coastal (estuarine/marine)) and coastal sediment from an agricultural region of Bahia State, Brazil. This area contains a larger number of eucalyptus plantations where sulfluramid is suspected to be applied. Soil, leaves, and coastal water (marine/estuarine) contained ∑PFAS concentrations of up to 5400 pg g-1, 979 pg g-1, and 1020 pg L-1, respectively, with PFAS profiles generally dominated by PFOS and perfluorooctane sulfonamide (FOSA). Coastal sediment contained ∑PFAS concentrations of up to 198 pg g-1, with PFOS, FOSA, and perfluorooctanoic acid (PFOA) being the most frequently observed PFASs. These substances are all potential EtFOSA transformation products, pointing to sulfluramid as a possible source. In riverine water, ∑PFAS concentrations of up to 8930 pg L-1 were observed. PFOS and PFOA were detected in all river water samples. Groundwater also exhibited PFAS contamination (5730 pg L-1 ∑PFASs), likely from sulfluramid use. The observation of other PFASs (e.g. perfluorobutanoic acid) in freshwater suggests that other PFAS sources (in addition to sulfluramid) may be important in this region. Overall, these data support the hypothesis that sulfluramid use contributes to the occurrence of PFASs in the Brazilian environment.

Biotransformation of 8:2 polyfluoroalkyl phosphate diester in gilthead bream (Sparus aurata)

Polyfluoroalkyl phosphate esters (PAPs) are high production volume surfactants used in the food contact paper and packaging industry. PAPs may transform to persistent perfluoroalkyl carboxylic acids (PFCAs) under biotic conditions, but little is known about their fate and behavior in aquatic organisms. Here we report for the first time on the uptake, tissue distribution, and biotransformation of 8:2 polyfluoroalkyl phosphate diester (8:2 diPAP) in fish. Gilt-head bream (Sparus aurata) were dosed via the diet (8:2 diPAP at 29μg/g) for 7days, during which time 8:2 diPAP and its transformation products were monitored in plasma, liver, muscle, gills, bile and brain. 8:2 diPAP tended to accumulate in liver, plasma and gills, and to a lesser extent in muscle, bile and brain. Several transformation products (observed previously in other organisms) were also observed in most tissues and biofluids, including both saturated and unsaturated fluorotelomer acids (8:2 FTCA, 8:2 FTUCA, 7:3 FTCA), and perfluorooctanoic acid (PFOA). 8:2 FTCA was the major metabolite in all tissues/biofluids, except for bile, where PFOA occurred at the highest concentrations. Unexpectedly high PFOA levels (up to 3.7ng/g) were also detected in brain. Phase 2 metabolites, which have been reported in fish following exposure to fluorotelomer alcohols, were not observed in these experiments, probably due to their low abundance. Nevertheless, the detection of PFOA indicates that exposure to PAPs may be an indirect route of exposure to PFCAs in fish.