Determination of perfluorinated compounds in wastewater and river water samples by mixed hemimicelle-based solid-phase extraction before liquid chromatography–electrospray tandem mass spectrometry detection

An overview on human exposure, toxicity, solid-phase microextraction and adsorptive removal of perfluoroalkyl carboxylic acids (PFCAs) from water matrices

Perfluoroalkyl carboxylic acids (PFCAs) are sub-class of perfluoroalkyl substances commonly detected in water matrices. They are persistent in the environment, hence highly toxic to living organisms. Their occurrence at trace amount, complex nature and prone to matrix interference make their extraction and detection a challenge. This study consolidates current advancements in solid-phase extraction (SPE) techniques for the trace-level analysis of PFCAs from water matrices. The advantages of the methods in terms of ease of applications, low-cost, robustness, low solvents consumption, high pre-concentration factors, better extraction efficiency, good selectivity and recovery of the analytes have been emphasized. The article also demonstrated effectiveness of some porous materials for the adsorptive removal of the PFCAs from the water matrices. Mechanisms of the SPE/adsorption techniques have been discussed. The success and limitations of the processes have been elucidated.

Plasma-assisted degradation of a short-chain perfluoroalkyl substance (PFAS): Perfluorobutane sulfonate (PFBS)

This study investigates the degradation of perfluorobutane sulfonate (PFBS), a chemical compound belonging to a group of per- and polyfluoroalkyl substances (PFAS), by gas-phase electrical discharge plasma. Plasma alone was ineffective in degrading PFBS due to its poor hydrophobicity, which inhibited the compound from accumulating at the plasma-liquid interface, the region of chemical reactivity. To overcome bulk liquid mass transport limitations, a surfactant, hexadecyltrimethylammonium bromide (CTAB), was introduced to interact with and transport PFBS to the plasma-liquid interface. In the presence of CTAB, ∼99% of PFBS was removed from the bulk liquid and concentrated at the interface, where 67% of the concentrate was degraded and 43% of that amount was defluorinated within one hour. PFBS degradation was further improved by optimizing the surfactant concentration and dosage. Experiments with a range of cationic, non-ionic, and anionic surfactants revealed that the PFAS-CTAB binding mechanism is predominantly electrostatic. A mechanistic understanding of the PFAS-CTAB complex formation, its transport to and destruction at the interface is proposed, alongside the chemical degradation scheme, which includes the identified degradation byproducts. This study shows that surfactant-assisted plasma treatment is one of the most promising techniques for destroying short-chain PFAS in contaminated water.

A new dual-recognition strategy for hybrid ratiometric and ratiometric sensing perfluorooctane sulfonic acid based on high fluorescent carbon dots with ethidium bromide

In this work, a novel strategy for perfluorooctane sulfonic acid (PFOS) detection was established by using a ratiometric nanosensor with the combination of fluorescence and second-order scattering (SOS). The practical ratiometric nanosensor was synthesized simply by mixing fluorescent dye ethidium bromide (EB) and nitrogen doped carbon dots (N-CDs) which was synthesized by a one-step hydrothermal method with Victoria Blue B, possessing three emission peaks at 472 nm, 560 nm and 600 nm under a single wavelength excitation of 280 nm, respectively. The EB served as the reference signal label, and the N-CDs, having response to the analytes, acted as the response signal label. To achieve ratiometric detection, the fluorescence emission of the N-CDs was turned off and the SOS emission was turned on with the addition of the target PFOS. To achieve colorimetric detection, with the help of EB, the fluorescence of the system changed from green to orange. Under the optimal conditions, the difference of F₄₇₂/I₅₆₈ of the nanosensor had good linearity against the concentrations of PFOS within a linear range of 0-2.0 μM. The limit of detection was as low as 27.8 nM, which was low enough for the detection of PFOS in water samples. The proposed method has been successfully applied to the detection of PFOS with RSD <1.67%. The results show that the as-prepared N-CDs/EB ratiometric nanosensor has potential application for the detection of PFOS in environmental monitoring.

Adsorption of perfluoroalkyl and polyfluoroalkyl substances (PFASs) from aqueous solution - A review

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) have gained increasingly global attention in recent years. Due to their unique amphiphilic properties and stability, PFASs are recognized as highly persistent, toxic, and environmentally bioaccumulative. Among several physicochemical technologies, adsorption has been extensively used and proved to be an effective method for removing PFASs from aqueous environment. In this review article, the technical feasibility of the use of different adsorbents, such as activated carbon, ion exchange resins, minerals, molecularly imprinted polymer (MIP), carbon nanotubes (CNTs), and a wide range of potentially low-cost biosorbents, for PFASs removal from water or wastewater is critically reviewed. The evaluation and comparison of their PFASs sorption behavior in terms of kinetics and isotherms is presented. The mechanisms involved in PFASs adsorption processes, such as diffusion, electrostatic interaction, hydrophobic interaction, ion exchange and hydrogen bond, are discussed. The effects of the parameters variability on sorption process are highlighted. Based on the literature reviewed, a few recommendations for future research on PFASs adsorption are also elaborated. Capsule: The adsorption behavior and mechanisms of perfluoroalkyl and polyfluoroalkyl substances (PFASs) on various adsorbents are reviewed.

Highly selective fluorescent visual detection of perfluorooctane sulfonate via blue fluorescent carbon dots and berberine chloride hydrate

As a kind of emerging persistent organic pollutants, perfluorooctane sulfonate (PFOS) and its salts have caused global ecosystem pollution. To develop rapid, sensitive and low-cost detection method of PFOS is of great importance. In this work, a novel sensing method has been proposed for the highly selective fluorescent visual detection of PFOS in aqueous solution based on carbon dots (CDs) and berberine chloride hydrate (BH). It was found that the fluorescence of CDs decreased apparently in the presence of berberine chloride hydrate in pH 6.09 Britton-Robinson (BR) buffer solution. When PFOS was added to the system, the fluorescence was restored slightly at 448 nm and enhanced apparently at 533 nm, but no phenomenon occurred with other perfluorinated compounds. As a consequence, an obviously distinguishable fluorescence color variation (from blue to light yellow) of solution was observed. Under the optimized experimental conditions, the enhanced fluorescence intensities at 533 nm are in proportion to the concentration of PFOS in the range of 0.22-50.0 μmol/L (R² = 0.9919), with a detection limit of 21.7 nmol/L (3σ). The proposed approach has been successfully applied to the detection of PFOS in environmental water samples with RSD ≤ 1.1%.

A novel mixed hemimicelles dispersive micro-solid phase extraction using ionic liquid functionalized magnetic graphene oxide/polypyrrole for extraction and pre-concentration of methotrexate from urine samples followed by the spectrophotometric method

Methotrexate (MTX) is an anticancer drug that is widely used in a variety of cancers including primary central nervous system lymphoma. It is also administrated in the treatment of some autoimmune diseases. A simple, accurate, sensitive, and precise mixed hemimicelles dispersive micro-solid phase extraction was proposed for MTX quantification in human urine samples. MTX was quantified by spectrophotometer after dispersive micro-solid phase extraction using ionic liquid functionalized magnetic graphene oxide/polypyrrole. Interactions of adsorbent and MTX were modeled by molecular docking and the interaction energy was predicted to be -8.35 kcal/mol. A larger absolute value of binding energy represents larger adsorption strength, indicating that graphene oxide nanosheets could perform higher adsorption strength toward MTX. The concentrations of MTX were proportional to analytical response in amounts ranging from 10 to 1000 ng/mL with a good correlation (R² = 0.99). Inter- and intra-day precisions and accuracies were within the acceptable limit according to FDA guideline (15% for biological determination). The recoveries were ranging from 89 to 93% and the method was specific for routine analysis of MTX. This protocol was applied to the urine of two patients under MTX therapy received an intravenous administration of 1 mg/kg/dose of MTX with acute lymphoblastic leukemia. The accuracy of the method was confirmed by HPLC measurements.

Using hydrodynamic model to predict PFOS and PFOA transport in the Daling River and its tributary, a heavily polluted river into the Bohai Sea, China

Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) are extremely persistent in the environment, and have the potential for long-range transport. The present study focused on the Daling River and its tributary, a larger river flowing into Liaodong Bay of the Bohai Sea. Recent studies have shown the elevated levels of PFOS and PFOA in the Daling River. Hence, the objective of this study was to investigate the seasonal changes, fate and transport modeling of PFOS and PFOA concentrations using one-dimensional DHI MIKE-11 river model. We designed three scenarios to assess the risk of PFOS and PFOA in surface water: the measured concentrations, constant maximum and the magnitude of a continuous constant load. The mean absolute errors divided by the mean of measured concentrations were 41-64% for PFOS and 29-36% for PFOA. The result indicated that PFOS and PFOA in the downstream of the Daling River would not reach a harmful level with the current load. The fluorochemical parks contributed an average of 44.57% of the total PFOS and 95.44% of the total PFOA flow that reached the estuary. The mass flow was observed as 1.74 kg y^-1 for PFOS and 40.57 kg y^-1 for PFOA to the Bohai Sea. These modeling results may be useful for monitoring the status and trends of emerging POPs and will help the determination of the risk to both humans and wildlife, in the estuarine and coastal areas of the Bohai Sea, China.

Magnetic Nanoparticles Interaction with Humic Acid: In the Presence of Surfactants

Adsorbed humic acid (HA) on surfaces of nanoparticles (NPs) will affect their transport, transfer, and fate in the aquatic environment, especially in the presence of surfactants, and thereby potentially alter exposures and bioavailable fractions of NPs and surfactants. This study investigated adsorption of HA on Fe3O4 NPs in the presence or absence of surfactant. Surfactant established a bridge connecting HA and Fe3O4 NPs, and significantly changed adsorption behavior of HA on NPs. Adsorption of HA in the absence of surfactant was 120.3 mg/g, but 350.0 mg/g and 146.5 mg/g in the present of CTAB (hexadecyl trimethylammonium bromide) and SDS (sodium dodecyl sulfate), respectively. Surfactants can form different stages (hemimicelles, mixed hemimicelles and admicelles) on Fe3O4 NPs by electrostatic and hydrophobic interactions, adsorption of HA was different for each of those stages. Adsorption of HA on surface of Fe3O4 NPs/CTAB was codetermined by hydrophobic, electrostatic interactions and ligand exchange. The presence of CTAB or SDS changed mechanisms for adsorption and effects of functional groups. Results of Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) indicated that carbohydrate carbon was important in adsorption of HA on Fe3O4 NPs in the presence of surfactants.

Preconcentration and determination of ranitidine hydrochloride in real samples by using modified magnetic iron oxide nanoparticles

This method shows a novel, fast, and simple magnetic solid-phase extraction (SPE) and spectrophotometric procedure for preconcentration and determination of ranitidine hydrochloride in human plasma and aquatic samples by using Fe3O4 nanoparticles (NPs) modified by sodium dodecyl sulfate (SDS) as an extractor. The unique properties of Fe3O4 NPs including high surface area and strong magnetism were utilized effectively in the magnetic SPE process. The determination method is based on the SDS-coated Fe3O4 NPs with extracted ranitidine-HCl, which was subsequently monitored spectrophotometrically at λmax = 320 nm. Effects of different parameters influencing the extraction efficiency of ranitidine-HCl including the pH value, amount of SDS, and Fe3O4 NPs, extraction time, desorption solvent, desorption time, and sample volume were optimized. Under optimized conditions, the method was successfully applied to the extraction of ranitidine-HCl from human plasma and aquatic samples. The extraction recovery in human plasma and different matrixes of waters were investigated and values of 89.0%–103.4% were obtained. The calibration graph for the determination of ranitidine-HCl was linear in the range of 0.025–1.50 μg mL−1 with R2 = 0.9946. The limit of detection of the proposed method was 7.5 × 10−3 μg mL−1. The repeatability and reproducibility (relative standard deviation) of the mentioned method were 0.83% and 1.22%, respectively. The experimental results showed that the proposed method was feasible for the analysis of ranitidine-HCl in environmental and biological samples.

Superparamagnetic Fe3 O4 @SiO2 core-shell composite nanoparticles for the mixed hemimicelle solid-phase extraction of benzodiazepines from hair and wastewater samples before high-performance liquid chromatography analysis

Magnetic Fe3 O4 /SiO2 composite core-shell nanoparticles were synthesized, characterized, and applied for the surfactant-assisted solid-phase extraction of five benzodiazepines diazepam, oxazepam, clonazepam, alprazolam, and midazolam, from human hair and wastewater samples before high-performance liquid chromatography with diode array detection. The nanocomposite was synthesized in two steps. First, Fe3 O4 nanoparticles were prepared by the chemical co-precipitation method of Fe(III) and Fe(II) as reaction substrates and NH3 /H2 O as precipitant. Second, the surface of Fe3 O4 nanoparticles was modified with shell silica by Stober method using tetraethylorthosilicate. The Fe3 O4 /SiO2 composite were characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and vibrating sample magnetometry. To enhance their adsorptive tendency toward benzodiazepines, cetyltrimethylammonium bromide was added, which was adsorbed on the surface of the Fe3 O4 /SiO2 nanoparticles and formed mixed hemimicelles. The main parameters affecting the efficiency of the method were thoroughly investigated. Under optimum conditions, the calibration curves were linear in the range of 0.10-15 μgmL(-1) . The relative standard deviations ranged from 2.73 to 7.07%. The correlation coefficients varied from 0.9930 to 0.9996.

Triple-wavelength overlapping resonance Rayleigh scattering method for facile and rapid assay of perfluorooctane sulfonate

In the present study, a novel triple-wavelength overlapping resonance Rayleigh scattering (TWO-RRS) method had been well established to detect perfluorooctane sulfonate (PFOS). We found that crystal violet (CV) could react with PFOS to form 1:1 ion-association complex by electrostatic attraction and hydrophobic effect over a wide pH range (5.0∼11.0) in less than 60 s. The complexes would further self-aggregated into nanoparticles [CV-PFOS]n. Based on this phenomenon, not only the absorption and Raman spectra were changed but also the resonance Rayleigh scattering (RRS) intensities were significantly enhanced. And three new RRS peaks located at 327, 492, and 654 nm were clearly observed, respectively. At the same time, it was found that both the enhanced single-wavelength resonance Rayleigh scattering (SW-RRS) and TWO-RRS intensities against the concentration of PFOS showed an excellent correlation. The detection limits for the three single peaks were 27.4 nmol L(-1) (13.7 μg L(-1), 327 nm), 27.5 nmol L(-1) (13.8 μg L(-1), 492 nm), and 31.4 nmol L(-1) (15.7 μg L(-1), 654 nm), and for TWO-RRS method was 5.9 nmol L(-1) (3.0 μg L(-1)). Moreover, it could be applied to determine PFOS water samples successfully.

Perfluorooctane sulfonate release pattern from soils of fire training areas in Australia and its bioaccumulation potential in the earthworm Eisenia fetida

Aqueous film-forming foams (AFFF) are used to extinguish hydrocarbon fuel fires. Certain AFFF products such as 3M Lightwater contain perfluorooctane sulfonate (PFOS) as the active ingredient which is highly persistent in the environment and is thus globally prevalent. With thousands of tons of soils potentially contaminated with PFOS stockpiled at a number of sites in Australia, the lack of reliable information on bioavailability of this recalcitrant contaminant constrains the application of a risk-based strategy for managing such soils. In this study, the PFOS release pattern from soils collected from the contaminated sites of fire training areas and its bioaccumulation potential in earthworm were investigated. The study was conducted at two temperatures (25 and 37 °C) and 60 % of the maximum water-holding capacity of soils. The greatest release into water was found to occur from the soil having the highest PFOS concentration, 16.17 μg g(-1) (Tindal FTA064), thereby demonstrating the role of contaminant loading on release behaviour. The release could also be related to the soil physico-chemical properties. The maximum amount of PFOS was desorbed from the soil with the lowest clay and organic matter content. Bioaccumulation of PFOS in earthworms (Eisensia fetida) as expressed by the bioaccumulation factor (BAF) was found to be highest from soil with the lowest PFOS concentration (RBD soil). The range of BAF found in our study was 1.23 (spiked Tindal SS01 soil) to 13.9 (field contaminated RBD soil). Our study suggests that PFOS could indeed pose a potential risk to ecological safety of soil if present even at concentrations as low as 0.8 μg g(-1) since the highest bioaccumulation factor was found to be from such a soil (field contaminated RBD).

Application of surfactant-templated ordered mesoporous material as sorbent in micro-solid phase extraction followed by liquid chromatography-triple quadrupole mass spectrometry for determination of perfluorinated carboxylic acids in aqueous media

In the present study, micro-solid phase extraction (µ-SPE) followed by liquid chromatography-triple tandem mass spectrometery (LC-MS/MS) was developed for the determination of perfluorocarboxylic acids (PFCAs) at trace levels in water samples. The µ-SPE device comprised of a porous polypropylene membrane bag containing 5mg sorbent. The membrane bag acted as a clean-up filter and prevented matrix compounds from interfering with the extraction process. Analysis was carried out by LC-MS/MS in negative electrospray ionization mode. MS/MS parameters were optimized for multiple reaction monitoring. Calcined and non-calcined MCM-41, as silica-ordered mesoporous materials, were used as sorbents in µ-SPE for the extraction of five PFCAs-perfluoropentanoic acid (PFPA), perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorodecanoic acid (PFDA)-from aqueous media. The performances of these two sorbents were compared with other sorbents such as octadecylsilane (C18) modified silica, HayeSep-A, HayeSep-B, and Porapak-R. It was found that non-calcined MCM-41 showed better extraction performance for the analytes considered. Parameters influencing extraction efficiency, such as desorption time, extraction time, desorption solvent, and salt concentration, were investigated. The effect of the matrix on MS signals (suppression or enhancement) was also evaluated. Only minor effects on ionization efficiencies were observed. The developed method proved to be convenient and offered good sensitivity and reproducibility. The limits of detection ranged from 0.02 to 0.08ng L(-1), with a relative standard deviations between 1.9 and 10.5. It was successfully applied to the extraction of PFCAs in river and rain water samples. As expected from the ubiquitous nature of PFCAs, contamination at low levels was detected for some analytes in the samples (with the highest concentration recorded for PFOA). Satisfactory relative recoveries ranging between 64% and 127% at spiking levels of 10ng L(-1) of each analyte were obtained.

Preparation and use of maize tassels' activated carbon for the adsorption of phenolic compounds in environmental waste water samples

The determination and remediation of three phenolic compounds bisphenol A (BPA), ortho-nitrophenol (o-NTP), parachlorophenol (PCP) in wastewater is reported. The analysis of these molecules in wastewater was done using gas chromatography (GC) × GC time-of-flight mass spectrometry while activated carbon derived from maize tassel was used as an adsorbent. During the experimental procedures, the effect of various parameters such as initial concentration, pH of sample solution, eluent volume, and sample volume on the removal efficiency with respect to the three phenolic compounds was studied. The results showed that maize tassel produced activated carbon (MTAC) cartridge packed solid-phase extraction (SPE) system was able to remove the phenolic compounds effectively (90.84-98.49%, 80.75-97.11%, and 78.27-97.08% for BPA, o-NTP, and PCP, respectively). The MTAC cartridge packed SPE sorbent performance was compared to commercially produced C18 SPE cartridges and found to be comparable. All the parameters investigated were found to have a notable influence on the adsorption efficiency of the phenolic compounds from wastewaters at different magnitudes.

Fluorous solid-phase extraction (F-SPE) as a pilot tool for quantitative determination of perfluorochemicals in water samples coupled with liquid chromatography-tandem mass spectrometry

As a large group of stable existing organofluorine compounds widely present in the environment, perfluorochemicals (PFCs) could pose potential adverse effects on human health.

Eggshell membrane-based biotemplating of mixed hemimicelle/admicelle as a solid-phase extraction adsorbent for carcinogenic polycyclic aromatic hydrocarbons

A new solid-phase extraction (SPE) format was demonstrated, based on eggshell membrane (ESM) templating of the mixed hemimicelle/admicelle of linear alkylbenzenesulfonates (LAS) as an adsorbent for the enrichment of carcinogenic polycyclic aromatic hydrocarbons (PAHs) in environmental aqueous samples. The LAS mixed hemimicelle/admicelle formation and SPE of the target PAHs were conducted simultaneously by adding the organic target and LAS through a column filled with 500 mg of ESM. The effect of various factors, including LAS concentration, solution pH, ionic strength, and humic acid concentration on the recoveries of PAHs were investigated and optimized. The results showed that LAS concentration and solution pH had obvious effect on extraction of PAHs, and the recoveries of PAHs compounds decreased in the presence of salt and humic acid. Under the optimized analytical conditions, the present method could respond down to 0.1-8.6 ng/L PAHs with a linear calibration ranging from 0.02 to 10 μg/L, showing a good PAHs enrichment ability with high sensitivity. The developed method was used satisfactorily for the detection of PAHs in environmental water samples. The mixed hemimicelle/admicelle adsorbent exhibited high extraction efficiency to PAHs and good selectivity with respect to natural organic matter and was advantageous over commercial C₁₈ adsorbent, for example, high extraction yield, high breakthrough volume, and easy regeneration.

Adsorption behavior and mechanism of perfluorinated compounds on various adsorbents--a review

Perfluorinated compounds (PFCs) have drawn great attention recently due to their wide distribution in aquatic environments and potential toxic to animals and human beings. Adsorption not only is an effective technology to remove PFCs from water or wastewater, but also affects PFC distribution at solid-liquid interfaces and their fate in aquatic environments. This article reviews the adsorption behavior of different PFCs (mainly perfluorooctane sulfonate and perfluorooctanoate) on various adsorptive materials. Some effective adsorbents are introduced in detail in terms of their preparation, characteristics, effects of solution chemistry and PFC properties on adsorption. Adsorption mechanisms of PFCs on different adsorbents are summarized, and various interactions including electrostatic interaction, hydrophobic interaction, ligand exchange, and hydrogen bond are fully reviewed. The adsorbents with amine groups generally have high adsorption capacity for PFCs, and formation of micelles/hemi-micelles plays an important role in achieving high adsorption capacity of perfluorinated surfactants on some porous adsorbents. Hydrophobic interaction is mainly responsible for PFC adsorption, but the difference between PFCs and traditional hydrocarbons has not clearly clarified. This review paper would be helpful for the preparation of effective adsorbents for PFC removal and understanding interfacial process of PFCs during their transport and fate in aquatic environments.

Determination of residual nonsteroidal anti-inflammatory drugs in aqueous sample using magnetic nanoparticles modified with cetyltrimethylammonium bromide by high performance liquid chromatography

A simple and sensitive solid-phase extraction method for separation and preconcentration of trace amount of four nonsteroidal anti-inflammatory drugs (naproxen, indomethacin, diclofenac, and ibuprofen) using Fe₃O₄ magnetic nanoparticles modified with cetyltrimethylammonium bromide has been developed. For this purpose, the surface of MNP_s was modified with cetyltrimethylammonium bromide (CTAB) as a cationic surfactant. Effects of different parameters influencing the extraction efficiency of drugs including the pH, amount of salt, shaking time, eluent type, the volume of solvent, amount of adsorbent, sample volume, and the time of desorption were investigated and optimized. Methanol has been used as desorption solvent and the extracts were analysed on a reversed-phase octadecyl silica column using 0.02 M phosphate-buffer (pH = 6.02) acetonitrile (65 : 35 v/v) as the mobile phase and the effluents were measured at 202 nm with ultraviolet detector. The relative standard deviation (RSD%) of the method was investigated at three concentrations (25, 50, and 200 ng/mL) and was in the range of 3.98–9.83% (n = 6) for 50 ng/mL. The calibration curves obtained for studied drugs show reasonable linearity (R² > 0.99) and the limit of detection (LOD_s) ranged between 2 and 7 ng/mL. Finally, the proposed method has been effectively employed in extraction and determination of the drugs in biological and environmental samples.

Estimation of PFOS emission from domestic sources in the eastern coastal region of China

Perfluorooctane sulfonate (PFOS) and related chemicals (collectively "PFOS equivalents") have been released to the environment through widespread consumer use and disposal of PFOS-containing products like carpet, leather, textiles, paper, food containers, household cleansers, etc. Accordingly, in addition to PFOS-related industries, domestic activities may also considerably contribute to the PFOS emissions in the eastern coastal region of China, which has been characterized by high industrial input. In the present study, domestic emissions of PFOS equivalents derived from municipal wastewater treatment plants were estimated at the county level, using a regression model of domestic emission density with population density and per capita disposable income as independent variables. The total emission load of PFOS equivalents from domestic sources in the eastern coastal region of China was 381kg in 2010, and large cities were prominent as the emission centers. The domestic emission density averaged 0.37g/km(2)·a for the entire study area. Generally, the Beijing-Tianjin area, Pearl River Delta and Yangtze River Delta, as the most populous and economically developed areas in China, showed significantly higher emission density. Geographical variations within individual provinces were noteworthy. The average per capita discharge load of PFOS equivalents arising from domestic activities was 1.91μg/day per capita in the eastern coastal region of China, which is consistent with previous estimates in Korea, but lower than those calculated for developed countries. In comparison, the spatial distributions of provincial PFOS emissions from domestic and industrial sources were similar to each other; however, the latter was much larger for all the provinces.

Industrial source identification and emission estimation of perfluorooctane sulfonate in China

Perfluorooctane sulfonate (PFOS) and related chemicals (collectively "PFOS equivalents") are currently manufactured and used in a wide variety of industrial processes in China. Since 2003, the national annual production has increased dramatically to accommodate both domestic demands and ongoing overseas needs for metal plating, fire-fighting foams, photographic, semiconductor and aviation industries. Accordingly, PFOS-related industries are significant sources of PFOS to the environment in China, though little information is available. In the present study, industrial sources of PFOS in China were identified and emissions from major related industries, including PFOS manufacture, textile treatment, metal plating, fire-fighting and semiconductor industries, were evaluated. Contribution by various industrial sources and spatial distribution of the PFOS emission were discussed. It was estimated that the total emission of PFOS equivalents in China was 70t in 2010. Industrial use of PFOS in metal plating was identified as the largest source of PFOS pollution at the national level, followed by textile treatment, fire-fighting, PFOS manufacture and semiconductor industry. At the regional level, greater contributions were made by metal plating and textile treatment in most provinces of eastern China, while in the western part of China and several northeastern provinces fire-fighting was the predominant source. The contribution by PFOS manufacture was considerable in Hubei and Fujian provinces. Total emission, emission density and emission intensity showed geographical variations. In general, the eastern coastal provinces, as the most intensively industrialized regions of China, were characterized by significantly higher emission rates, emission density and emission intensity than those in western and northern China. Available monitoring data of PFOS concentrations in surface water of China reflected a similar distribution pattern, confirming that manufacture and industrial uses were crucial sources of PFOS pollution which would cause significant risks in the environment.

NMR spectroscopy and chemometrics as a tool for anti-TNFα activity screening in crude extracts of grapes and other berries

The identification of active ingredients in crude plant extracts offers great advantages. In this study, nuclear magnetic resonance and chemometrics were used for the screening of in vitro anti-TNFα activity in different berry types. Solid phase extraction was applied and the resulting water, methanol-water (1:1), and methanol fractions were tested for the activity. The methanol-water fraction contained most of the phenolics and showed significantly higher activity than the other two fractions. In the second phase of this study, grapes from 'Trincadeira', 'Touriga Nacional', and 'Aragonês', at four developmental stages were metabolically classified and tested for the TNFα inhibition. The initial stages of grape development, green and veraison, were found more active against TNFα production as compared to the later ripe and harvest stages. Among the cultivars, 'Touriga Nacional' was found to be the most potent inhibitor. Different multivariate data analyses algorithms based on projections to latent structures were applied to correlate the NMR and TNFα inhibition data. The variable importance in the projections plot showed that phenolics like quercetin, myricetin, (+)-catechin, (-)-epicatechin, caftarate, and coutarate, were positively correlated with high activity. This work demonstrates the great potential of NMR spectroscopy in combination with chemometrics for the screening of large set of crude extracts, to study the effects of different variables on the activity, and identifying active compounds in complex mixtures like plant extracts. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11306-012-0406-8) contains supplementary material, which is available to authorized users.

Environmental impact of phthalic acid esters and their removal from water and sediments by different technologies--a review

This article describes the most recent methods developed to remove phthalic acid esters (PAEs) from water, wastewater, sludge, and soil. In general, PAEs are considered to be endocrine disrupting chemicals (EDCs), whose effects may not appear until long after exposure. There are numerous methods for removing PAEs from the environment, including physical, chemical and biological treatments, advanced oxidation processes and combinations of these techniques. This review largely focuses on the treatment of PAEs in aqueous solutions but also reports on their treatment in soil and sludge, as well as their effects on human health and the environment.