Analysis Of Perfluoroalkyl Substances Research Articles

Development and validation of a novel HPLC-MS/MS method for the quantitative determination of PFASs in non-hazardous solid waste samples

Perfluoroalkyl substances (PFASs) are a heterogeneous group of fluorinated synthetic compounds characterised by the presence of a hydrophobic carbonyl chain at different fluorination rates and by a terminal hydrophilic group. Because of their persistence and mobility, PFASs have been widely detected in ecosystems and living organisms, leading to their classification as persistent organic pollutants (POPs). Hence, monitoring the PFASs content in solid waste meant for disposal in non-hazardous landfills can be crucial, since leachate can pose a significant pollution threat to farmlands and aquifers.Therefore, a QuEChERS and SPE pretreatment with HPLC-MS/MS detection method for 10 different PFASs in solid waste samples was developed in this study. Different sample preparation approaches have been evaluated, taking into account the lack in the literature of this complex matrix.An innovative application using the Captiva EMR cartridge for the clean up (designed to be applied to lipidic matrix) was proposed and a multiresidual HPLC-MS/MS method for the analysis of PFASs in internal waters was extended to the investigation of non-lipidic samples as solid wastes. The method was then validated through 6 blanks and 6 spiked samples, according to the UNI EN ISO/IEC 17025. The optimized method showed satisfactory performance with recoveries ranging from 89.8 % to 106.5 % and with LOD and LOQ ranging between 0.0023 – 0.09 µg/L and 0.006 – 0.13 µg/L, respectively, for each of the PFASs under consideration. In addition, this approach demonstrated to be reliable and time consuming due to its capability for determining PFASs in waters and in solid wastes simultaneously in a single chromatographic run.

Comprehensive review of combustion ion chromatography for the analysis of total, adsorbable, and extractable organic fluorine.

Poly- and perfluoroalkyl substances (PFAS) are a class of persistent organic pollutants whose high stability and appreciable water solubility have led to near-global contamination. PFAS are bioaccumulative toxins that have been linked to a myriad of disorders and have been detected nearly universally in human blood. Liquid chromatography-tandem mass spectrometry is the most frequent method used for quantitation, though this typically only measures a few dozen of the >14000 known PFAS and has been shown to account for a small portion of the total organic fluorine present. Sum parameter methods such as total, extractable, and adsorbable organic fluorine have emerged as alternative measurements for PFAS determination. Combustion ion chromatography has become the preferred method for organofluorine measurement where the sorbent or extract containing PFAS is combusted and the emitted hydrofluoric acid (HF) is a measure of the cumulative organofluorine present. Herein we critically review the types of organofluorine measurement, their separation from the sample matrix, and key parameters of the analytical instrument that affect sensitivity, reproducibility, and recovery with regards to PFAS analysis.

Fluorine-functionalized magnetic amino microporous organic network for enrichment of perfluoroalkyl substances

Perfluoroalkyl substances (PFAS) are persistent organic pollutants that pose significant risks to human health and the environment. Efficient and selective enrichment of these compounds was crucial for their accurate detection and quantification in complex matrices. Herein, we report a novel magnetic solid-phase extraction (MSPE) method using fluorine-functionalized magnetic amino-microporous organic network (Fe3O4@MONNH2@F7) adsorbent for the efficient enrichment of PFAS from aqueous samples. The core-shell Fe3O4@MONNH2@F7 nanosphere was synthesized, featuring magnetic Fe3O4 nanoparticles as the core and a porous amino-functionalized MONs coating as the shell, which was further modified by fluorination. The synthesized adsorbent material exhibited high specific surface area, hydrophobicity, and abundant fluorine groups, facilitating efficient and selective adsorption of PFAS via electrostatic attraction, hydrophobic-hydrophobic interactions, fluorine-fluorine interactions, π-CF interactions and hydrogen bonding. Furthermore, the MSPE method coupled with ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) allowed for the rapid, sensitive, and accurate determination of ultra-trace PFAS in real water samples, human serum, and human follicular fluid. Under optimal conditions, the established MSPE method demonstrated a linear range (2 to 2000 ng L−1), with a correlation coefficient exceeding 0.9977, low limits of detection ranging from 0.54 to 1.47 ng L−1, with a relative standard deviation (RSD) < 9.1%. Additionally, the method showed excellent performance in complex real samples (recovery ratio of 81.7 to 121.6 %). The adsorption mechanism was investigated through kinetic, isotherm, and molecular simulation studies, revealing that the introduction of fluorine groups enhanced the hydrophobic interaction and fluorine-fluorine attraction between the adsorbent and PFAS. This work provides a proof-of-concept strategy for designing adsorbent materials with high efficiency and selectivity by post-modification, which has great potential for the detection and analysis of PFAS in complex samples.

Studies of Potential Migration of Hazardous Chemicals from Sustainable Food Contact Materials.

In recent years, due to modern techniques for the distribution, transport, and retail sale of food, the production of large amounts of non-biodegradable and bioaccumulative packaging waste has become a major environmental issue. To address this issue, new food packaging materials based on renewable biomass have been studied as eco-friendly, biodegradable, and biocompatible alternatives to synthetic materials. However, although these materials are not petrochemical derivatives, the presence of contaminants cannot be excluded. This work aims to extend the knowledge on bio-based packaging materials, researching the presence of contaminants potentially able to migrate to food at concentrations of concern. In this study, we focus on two classes of contaminants, organophosphate esters (OPEs) and perfluoroalkyl substances (PFASs), carrying out migration tests toward different simulants, according to the current European regulation. PFAS analysis was performed using high-resolution liquid chromatography coupled to ion trap-tandem mass spectrometry (QTrap). OPE analyses were performed both by gas chromatography-mass spectrometry (GC-MS) and high-resolution liquid chromatography coupled to triple quadrupole mass spectrometry (TQMS). Preliminary findings demonstrate the release of toxic OPEs and PFASs from bio-based food packaging, highlighting the need to investigate the presence of potentially harmful chemicals in these materials.

Assessing the performance of a targeted absolute quantification isotope dilution liquid chromatograhy tandem mass spectrometry assay versus a commercial nontargeted relative quantification assay for detection of three major perfluoroalkylsin human blood.

Isotope dilution ultrahigh-performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS) is commonly used for trace analysis of polyfluoroalkyl and perfluoroalkyl substances (PFAS) in difficult matrices. Commercial nontargeted analysis of major PFAS where relative concentrations are obtained cost effectively is rapidly emerging and is claimed to provide comparable results to that of absolute quantification using matrix matched calibration and isotope dilution UHPLC-MS/MS. However, this remains to be demonstrated on a large scale. We aimed to assess the performance of a targeted absolute quantification isotope dilution LC-MS/MS assay versus a commercial nontargeted relative quantification assay for detection of three major PFAS in human blood. We evaluated a population-based cohort of 503 individuals. Correlations were assessed using Spearman's rank correlation coefficients (rho). Precision and bias were assessed using Bland-Altman plots. For perfluorooctane sulfonic acid, the median concentrations were 5.10ng/mL (interquartile range [IQR] 3.50-7.24 ng/mL), the two assays correlated with rho 0.83. For perfluorooctanoic acid, the median concentrations were 2.14 ng/mL (IQR 1.60-3.0ng/mL), the two assays correlated with rho 0.92. For perfluorohexanesulfonate, the median concentrations were 5.5ng/mL (IQR 2.50-11.61 ng/mL), the two assays correlated with rho 0.96. The Bland-Altman statistical test showed agreement of the mean difference for the majority of samples (97-98%) between the two assays. Absolute plasma concentrations of PFAS obtained using matrix matched calibration and isotope dilution UHPLC-MS/MS show agreement with relative plasma concentrations from a nontargeted commercial platform by Metabolon. We observed striking consistency between the two assays when examining the associations of the three PFAS with cholesterol, offering additional confidence in the validity of utilizing the nontargeted approach for correlations with various health phenotypes.

First Investigation of the Physiological Distribution of Legacy and Emerging Perfluoroalkyl Substances in Raw Bovine Milk According to the Component Fraction.

Bovine milk is a pillar of the human diet and plays a key role in the nutrition of infants. Perfluoroalkyl substances (PFASs) are well-recognized highly stable organic compounds that are able to pollute ecosystems persistently and threaten both human and animal health. The study aimed to analyze the distribution of 14 PFASs within the milk matrix by comparing their content in whole milk, and its skimmed and creamed fractions. Raw milk samples were individually collected from 23 healthy cows (10 primiparous and 13 multiparous) reared on a farm in Northern Italy not surrounded by known point sources of PFASs. Each sample was fractioned in whole, skim, and cream components to undergo PFAS analysis using liquid chromatography-high-resolution mass spectrometry. All samples contained at least one PFAS, with perfluorobutanoic acid (PFBA) being the primary contaminant in all three fractions, followed by perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA). PFOS was shown to be significantly (p < 0.001) more concentrated in cream than in raw and skimmed milk. Multiparous cows showed a higher frequency of positive samples in all analyzed fractions. Further research is necessary to assess the risk of dairy diets and high-fat dairy products and to investigate the toxicological effects of PFASs on cattle, even in environments without known PFAS sources.

Losses of Ultrashort- and Short-Chain PFAS to Polypropylene Materials

Losses of long-chain poly-/per-fluoroalkyl substances (PFAS) due to adsorption on polypropylene (PP) materials have been reported in the literature. However, there is a lack of information on losses of ultrashort-/short-chain PFAS to PP materials, particularly in environmentally relevant conditions. In this study, we evaluated the losses of ultrashort-chain perfluoropropionic acid (PFPrA) and two short-chain PFAS, viz., perfluorobutanoic acid (PFBA) and perfluorobutanesulfonic acid (PFBS), to PP. Losses up to 20 ± 1% were observed for the studied PFAS after 24 h from 100 μg/L solutions. Losses varied greatly between PP tubes of different brands, probably due to differences in the availability of adsorption sites. Several processes were involved in the adsorptive losses of the three compounds. For example, charge screening and hydrophobic interactions affected the behavior of PFBS and PFBA. Lower losses observed in methanol and wastewater can be explained by the higher PFAS solubility and competition with other organics, respectively. This study highlights that laboratory-specific PFAS losses shall be carefully considered as they can prevent accurate trace analysis of short-chain PFAS. Our results will also help to improve the accuracy of future monitoring and adsorption studies of ultrashort-/short-chain PFAS.

Target and untargeted screening of perfluoroalkyl substances in biota using liquid chromatography coupled to quadrupole time of flight mass spectrometry

Perfluoroalkyl substances (PFAS) are known to bioaccumulate and trigger adverse effects in marine birds. This study develops an extraction and analytical methodology for the target/untargeted analysis of PFAS in eggs of Yellow-legged gull (Larus michahellis) and Audouin's gull (Larus audouinii) and blood of Greater flamingo (Phoenicopterus roseus), which are used as bioindicators of organic chemical pollution. Samples were extracted by ultrasonication with acetonitrile and cleaned-up with activated carbon, and analysis was performed by ultra-high-performance liquid chromatography coupled to a quadrupole-time of flight mass spectrometer (UHPLC-Q-TOF) with negative electrospray ionization. Data-independent acquisition (DIA) was performed through full-scan acquisition to obtain MS1 at 6 eV and MS2 at 30 eV. In a first step, quantitative analysis of 25 PFAS was performed using 9 mass-labelled internal standard PFAS and quality parameters of the method developed are provided. Then, an untargeted screening workflow is proposed using the high-resolution PFAS library database from NORMAN to identify new chemicals through accurate mass measurement of MS1 and MS2 signals. The method permitted to detect several PFAS at concentrations ranging from 0.45 to 55.2 ng/g wet weight in gull eggs and from 0.75 to 125 ng/mL wet weight in flamingos’ blood, with PFOS, PFOA, PFNA, PFUdA, PFTrDA, PFDoA, PFHxS and PFHpA the main compounds detected. In addition, perfluoro-p-ethylcyclohexylsulfonic acid (PFECHS, CAS number 646-83-3) and 2-(perfluorohexyl)ethanol (6:2 FTOH, CAS number 647-42-7) were tentatively identified. The developed UHPLC-Q-TOF target/untargeted analytical approach increases the scope of PFAS analysis, enabling a better assessment on contaminant exposure and promoting the use of bird species as bioindicators of chemical pollution.

Novel perfluoroalkyl substances (PFAS) discovered in whole blood using automated non-targeted analysis of dried blood spots

A small subset of per- and polyfluoroalkyl substances (PFAS) are routinely screened in human blood. These compounds generally explain <50 % of the total PFAS in human blood. The percentage of known PFAS in human blood has been decreasing as replacement PFAS and more complex PFAS chemistries are introduced to the market. Most of these novel PFAS have not been previously identified. Non-targeted methods are required to characterize this “dark matter” PFAS. Our objective was to apply non-targeted PFAS analysis to human blood to gain an understanding about the sources, concentrations, and toxicity of these compounds. A high-resolution tandem mass spectrometry (HRMS) and software workflow for PFAS characterization in dried blood spots is reported. Dried blood spots are a less invasive collection technique compared to venous blood draws, allowing collection from vulnerable populations. Biorepositories of archived dried blood spots are available internationally from newborns and present opportunities to study prenatal exposure to PFAS. In this study, dried blood spot cards were analyzed using iterative MS/MS by liquid chromatography HRMS. Data processing was conducted using FluoroMatch Suite including a visualizer tool that presents homologous series, retention time vs m/z plots, MS/MS spectra, feature tables, annotations, and fragments for fragment screening. The researcher performing data-processing and annotation was blinded to the fact that standards were spiked in, and was able to annotate 95 % of standards spiked on dried blood spot samples, signifying a low false negative rate using FluoroMatch Suite. A total of 28 PFAS (20 standards and 4 exogenous compounds) were detected across five homologous series with Schymanski Level 2 confidence. Of these 4, 3 were perfluoroalkyl ether carboxylic acids (PFECA), a chemical class of PFAS which is increasingly being detected in environmental and biological matrices but is not currently screened in most targeted analysese. A further 86 potential PFAS were detected using fragment screening. PFAS are extremely persistent and widespread yet remain largely unregulated. Our findings will contribute to an improved an understanding of exposures. Application of these methods in environmental epidemiology studies have the potential to inform policy with regards to PFAS monitoring, regulation, and individual-level mitigation strategies.

Interlaboratory Comparison Investigations (ICIs) and External Quality Assurance Schemes (EQUASs) for human biomonitoring of perfluoroalkyl substances (PFASs) in serum as part of the quality assurance programme under HBM4EU

Perfluoroalkyl substances (PFASs) are of very high concern due to their persistence and accumulative behaviour as well as their manifold adverse health effects. Human biomonitoring (HBM) based on the determination of PFASs in serum samples is an adequate and established strategy for exposure and risk assessment of the population. The suspected health risks associated with exposure levels in the general population call for reliable HBM data verified by Quality Assurance and Quality Control (QA/QC) measures. PFASs were among the chemicals selected as priority substances in HBM4EU, a pan-European project to harmonize and advance HBM within 30 European countries. For this purpose, the analytical comparability and accuracy of PFASs-analysing laboratories was assessed in a QA/QC programme comprising Interlaboratory Comparison Investigations (ICIs) and External Quality Assurance Schemes (EQUASs). This paper presents the evaluation process and discusses the results of four ICI/EQUAS rounds for the determination of eight perfluoroalkyl carboxylic acids and four perfluoroalkyl sulfonic acids (PFBS, PFHxS, PFHpS, PFOS) in serum. All 21 participating laboratories achieved satisfactory results for at least six of these biomarkers, although low limits of quantification (of about 0.1 μg/L) were required to quantify serum PFAS levels at general population exposure levels. The mean relative standard deviation of the participants' results (study RSDR) significantly improved from 22 % to 13 % over all PFAS biomarkers in the course of the four rounds. This QA/QC programme succeeded in establishing a network of laboratories with high analytical comparability and accuracy for the analysis of PFASs across 12 European countries.

The relationship between multiple perfluoroalkyl substances and cardiorespiratory fitness in male adolescents.

Exposure to perfluoroalkyl substances (PFASs) is associated with a number of adverse health outcomes. However, the relationship between mixed and individual PFAS exposure and cardiorespiratory fitness (CRF) in adolescents remains unclear. We used cross-sectional data from 491 teenagers (aged 13-19years) from the 2003-2004 National Health and Nutrition Examination Survey (NHANES) and examined the association between mixed PFAS exposure and CRF via weighted quantile sum (WQS) regression. Maximal oxygen consumption (VO2max) was used to evaluate CRF. Multivariate linear regression was performed to investigate the relationship between each PFAS and VO2max as well as the relationship between PFAS exposure and the inflammation parameters and blood lipid content. Mediation analyses were performed to investigate possible explanations of the risk of low CRF due to PFAS exposure. The results showed that for males, mixed PFAS exposure was negatively related to VO2max (beta = - 0.80, 95% CI: - 1.53 to - 0.10, P = 0.028) and that of the PFASs, perfluorononanoic acid (PFNA) had the greatest influence on VO2max. In the individual PFAS analysis, PFNA was negatively related to VO2max in male adolescents (beta = - 1.49, 95% CI: - 2.65 to - 0.32, P = 0.013). Additionally, significant relationships among serum PFNA levels and total cholesterol and the white blood cell (WBC) count were found. Mediation analyses revealed that WBC count accounted for 24.18% of the variation between PFNA level and CRF. The present results provide epidemiological evidence that exposure to PFASs, mainly PFNA, is negatively associated with CRF, possibly via alterations in WBC count.

Perfluorobutanoic acid (PFBA): No high-level accumulation in human lung and kidney tissue.

Perfluorobutanoic acid (PFBA) belongs to the complex group of synthetic perfluoroalkyl substances (PFAS) which have led to ubiquitous environmental contamination. While some of the long-chain compounds accumulate in the human body, the short-chain compound PFBA was found to have a relatively short half-life in blood of a few days, in agreement with relatively low PFBA serum/plasma levels of roughly 0.01ng/ml in European studies. Surprisingly, very high median levels of PFBA of 807 and 263ng/g tissue for human lung and kidney autopsy samples, respectively, were reported in a paper of Pérez et al. (2013). This would question the concept of PFAS blood analysis reflecting the body burden of these compounds. To verify the results of high PFBA tissue accumulation in humans, we have analyzed PFBA in a set of 7 lung and 9 kidney samples from tumor patients with a different method of quantification, using high-resolution mass spectrometry with the accurate mass as analytical parameter. The only human sample with a quantifiable amount of PFBA (peak area more than twice above the analytical background signals) contained approximately 0.17ng/g lung tissue. In the light of our results and considering the analytical problems with the short-chain compound PFBA exhibiting only one mass fragmentation, it appears to be likely that PFBA is not accumulating on a high level in human lung and kidney tissue. In general, the analysis of short-chain PFAS in complex matrices like food or tissue is very challenging with respect to instrumental quantification and possible sample contamination.

Occurrence and Ecological Risk Assessment of Perfluoroalkyl Substances (PFASs) in Water and Sediment from an Urban River in South China.

The chemical substances in urban rivers influence municipal water systems and reflect the recent use of these chemicals by humans or industries around the urban center. In this study, seven perfluoroalkyl substances (PFASs)-perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), 2-perfluorohexyl ethanol (6:2 FTOH), 2-perfluorooctyl ethanol (8:2 FTOH), and 6:2 chlorinated polyfluoroalkyl ether sulfonic acids (F-53B)-could be detected and quantified in river water and sediment samples collected from one tributary of the Liuxi River, which is part of Pearl River near Guangzhou in Guangdong province, South China. The fluxes of target PFASs into Liuxi River and their related ecological risks were further estimated. The total concentrations of PFASs (ΣPFASs) ranged from 506 to 3.16 × 103ng/L in water samples and 9.13 to 850ng/L in sediment samples. The two dominant PFAS compounds were 6:2 FTOH and PFHpA, which accounted for more than 90.0% of ΣPFASs in river water and sediment. Correlation analysis showed that there was significant positive correlation (p < 0.01) between two selected PFASs (e.g., between 6:2 FTOH and PFHpA). Correlation analysis of PFASs in river water and sediment indicated most PFASs in sediment were partitioned from river water. The ecological risk assessment indicated that the detected PFASs have a low risk (HQ < 0.1) in river water and sediment to Daphnia magna in the Liuxi River.

Legacy and Emerging Poly- and Perfluoroalkyl Substances in Finless Porpoises from East China Sea: Temporal Trends and Tissue-Specific Accumulation.

Perfluoroalkyl sulfonates (PFSAs), perfluoroalkyl carboxylates (PFCAs), and emerging alternatives and precursors of these compounds were determined in tissues of finless porpoise (Neophocaena asiaeorientalis sunameri) collected from East China Sea in 2009-2010 and 2018-2019. The median hepatic concentrations of emerging poly- and perfluoroalkyl substances (PFASs), including 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA), 8:2 chlorinated polyfluorinated ether sulfonate (8:2 Cl-PFESA), 2,3,3,3-tetrafluoro-2-propanoate (HFPO-DA), and 4,8-dioxa-3H-perfluorononanoate (ADONA) were 16.2, 2.16, < LOQ (limit of quantification) and < LOQ ng/g ww (wet weight), respectively. The concentrations of legacy substances, perfluorooctanesulfonate (PFOS), and perfluorooctanoate (PFOA), were 86.9 and 1.95 ng/g ww, respectively. The liver concentrations of 6:2 Cl-PFESA, HFPO-DA, and perfluorohexanesulfonate (PFHxS) increased with time between 2009-2010 and 2018-2019. Further, concentrations of PFOA showed a declining trend in finless porpoise, whereas PFOS and its precursor (i.e., perfluorooctane sulfonamide [FOSA]) showed an increasing trend with time between 2009-2010 and 2018-2019. Analysis of PFASs in nine different tissues/organs of finless porpoise (i.e., liver, heart, intestine, spleen, kidney, stomach, lung, muscle, and skin) revealed a similar distribution pattern between 6:2 Cl-PFESA and PFOS; however, the tissue distribution patterns differed between HFPO-DA and PFOA. The concentrations of PFAS alternatives in kidney were similar or lower than the prototype compounds PFOS and PFOA (i.e., 8:2 Cl-PFESA < 6:2 Cl-PFESA ≈ PFOS; HFPO-DA < PFOA), implying slow renal excretion of PFAS alternatives as that of legacy PFASs. The estimates of body burdens of PFASs in porpoises suggested comparable accumulation of PFAS alternatives and legacy PFSAs and PFCAs. This study provides novel information on temporal trends and tissue distribution of emerging PFASs in marine mammals in China.

The analysis of perfluoroalkyl substances at ppt level in milk and egg using UHPLC-MS/MS

ABSTRACT Per- and poly-fluorinated substances (PFASs) are man-made chemicals that have been used for a variety of applications and can end up in the food chain. New opinions on the risk assessment were recently published by the European Food Safety Authority, emphasising the need for more sensitive methods. From this, minimum required LOQs for the analytical method for analysis of milk and egg have been calculated for perfluorooctanoic acid (PFOA) and GenX (hexafluoropropylene oxide dimer acid, HFPO-DA). A fully validated method is described for analysis of 13 PFASs, including PFOA and HFPO-DA, in milk and egg. All compounds, except perfluorodecane sulphonate (PFDS), can be quantitatively determined in these matrices with a trueness ranging from 87% to 119% and a relative within-laboratory reproducibility between 12% and 41%. Also the method proved suitable for confirmation of the identity of the individual PFASs. The LOQ for HFPO-DA in milk and egg is 0.05 ng g−1, well below the calculated required LOQ. For PFOA in egg the determined LOQ is 0.025 ng g−1, nicely below the required level of 0.03 ng g−1. In milk the required LOQ was not achieved: 0.005 instead of 0.003 ng g−1. However, on six out of eight days an LOQ of 0.0025 ng g−1 was demonstrated. It is concluded that the required LOQs are achievable when instrument performance is optimal. The current method can be expanded with long chain PFASs by using a cellulose filter instead of the PTFE filter vials. The presented method was applied for a small-scale study in The Netherlands.

Internal exposure to perfluoroalkyl substances (PFASs) and biological markers in 101 healthy 1-year-old children: associations between levels of perfluorooctanoic acid (PFOA) and vaccine response

Perfluoroalkyl substances (PFASs) are a complex group of man-made chemicals with high stability and mobility leading to ubiquitous environmental contamination and accumulation in the food chain. In human serum/plasma samples, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) are the lead compounds. They are immunotoxic in experimental animals, and epidemiological studies provided evidence of a diminished production of vaccine antibodies in young children. However, information on children of the first year of age is missing but relevant, as they have a relatively high exposure if breastfed, and may have a higher susceptibility as their immune system is developing. In a cross-sectional study with 101 healthy 1-year-old children, internal levels of persistent organic pollutants and a broad panel of biological parameters were investigated at the end of the 1990s. Additional analysis of PFASs resulted in plasma levels (mean ± SD) of PFOA and PFOS of 3.8 ± 1.1 and 6.8 ± 3.4 µg/L, respectively, in the 21 formula-fed children, and of 16.8 ± 6.6 and 15.2 ± 6.9 µg/L in the 80 children exclusively breastfed for at least 4 months. The study revealed significant associations between levels of PFOA, but not of PFOS, and adjusted levels of vaccine antibodies against Haemophilus influenza type b (Hib, r = 0.32), tetanus (r = 0.25) and diphtheria (r = 0.23), with no observed adverse effect concentrations (NOAECs) determined by fitting a ‘knee’ function of 12.2, 16.9 and 16.2 µg/L, respectively. The effect size (means for PFOA quintiles Q1 vs. Q5) was quantified to be − 86, − 54 and − 53%, respectively. Furthermore, levels of PFOA were inversely associated with the interferon gamma (IFNɣ) production of ex-vivo lymphocytes after stimulation with tetanus and diphtheria toxoid, with an effect size of − 64 and − 59% (means Q1 vs. Q5), respectively. The study revealed no influence of PFOA and PFOS on infections during the first year of life and on levels of cholesterol. Our results confirmed the negative associations of PFAS levels and parameters of immune response observed in other epidemiological studies, with high consistency as well as comparable NOAECs and effects sizes for the three vaccine antibodies investigated, but for PFOA only. Due to reduction of background levels of PFASs during the last 20 years, children in Germany nowadays breastfed for a long duration are for the most part not expected to reach PFOA levels at the end of the breastfeeding period above the NOAECs determined.

Optimization of extraction methods for the analysis of PFOA and PFOS in the salty matrices during the wastewater treatment

Water bodies of numerous countries and regions in the world have been contaminated to various extents with the widespread production and usage of perfluoroalkyl substances (PFASs). Both domestic and industrial wastewaters become one of the important sources for the PFAS contaminations in natural water bodies, due to the incomplete treatment. Usually, the artificial wastewaters are complex and have high concentrations of inorganic salts, which could result in the matrix effects during the process of analysis for PFASs, contributing to quantify the target compounds inaccurately. In order to monitor the concentrations of PFAS contaminants precisely, suitable extraction methods were compared focusing on the matrix effects and characters of green analytical chemistry during the detection of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) existing with several common inorganic salts in wastewaters. The results showed that the analytical values of PFOA and PFOS were 2.8–3.6 times and 3.0–5.2 times higher than the theoretical values, respectively. The liquid-liquid extraction (LLE) and solid phase extraction (SPE) methods were used to reduce the matrix effects originated from inorganic salts, consequently the SPE method was confirmed as the optimal extraction method, based upon both the recoveries and green procedures. Combined with the application of the best parameters in real industrial wastewaters, indicating the present study would provide an accurate and green quantitative analysis of PFASs in salty wastewaters.

Losses of poly- and perfluoroalkyl substances to syringe filter materials

Syringe filters are used to separate solids from liquids prior to analysis of poly- and perfluoroalkyl substances (PFASs). This is a critical step in sample preparation, as losses of PFASs to the filter material can be significant and lead to underestimation. This study evaluated losses of 21 PFASs in three different matrices (methanol, MilliQ water, and water containing 10 mg L−1 dissolved organic carbon (DOC)) to six different types of syringe filter (0.45 and 0.22 μm). Regarding sample matrix, the lowest average ∑21PFAS losses were observed in methanol (13%), followed by DOC water (19%) and MilliQ water (26%). Regarding syringe filter material, the lowest average losses of ∑21PFAS in DOC water and MilliQ water were observed for a recycled cellulose filter (average losses 16% and 21%, respectively), while a polypropylene filter had the lowest ∑21PFAS losses in methanol (9%). A smaller polyethersulfone (PES) filter (0.22 μm, 17 mm Ø) showed significantly (p < 0.05) lower ∑21PFAS losses in DOC water (on average 7.3%) than a larger PES filter (0.45 μm, 37 mm Ø) (23%). In DOC water, losses to the filter increased by 3.8%, 5.1%, and 8.4% per CF2-moiety for C3-C11 perfluoroalkyl carboxylates (PFCAs), perfluoroalkyl sulfonates (PFSAs), and fluorotelomer sulfonic acids (FTSAs), respectively. Comparing different functional groups of PFASs, losses increased as follows: PFCAs < PFSAs < FTSAs < perfluorooctanesulfonamides (FOSAs). Thus, care is needed when including filtration in PFAS analysis, since losses can be significant (up to 100%) depending on the type of syringe filter, target PFAS, and matrix.

Rapid separation of isomeric perfluoroalkyl substances by high-resolution differential ion mobility mass spectrometry

The analysis of persistent organic pollutants, such as perfluoroalkyl substances (PFAS) including perfluorooctanoic acid (C7F15COOH, PFOA) and perfluorooctane sulfonate (C8F17SO3−, PFOS) by hyphenated chromatography-mass spectrometry methods is crucial in ensuring water quality. One of the challenges in PFOA and PFOS analysis is the separation of linear and branched isomers that have the same mass-to-charge ratio but can have different toxicological properties. Current methods that are used for separating isomeric PFAS require relatively long analysis times (min to h) that can limit throughput. An emerging technique for the direct analysis of isomeric compounds is differential mobility spectrometry (DMS), which can rapidly separate gas phase ions prior to detection by mass spectrometry (MS). However, an ion mobility-based method for the analysis of PFAS has not been reported in the literature. Herein, high-resolution DMS-MS is used to separate and detect isomeric PFAS compounds for the first time in a separation process that occurs in milliseconds. The resolution of isomeric peaks increased by over 200% and 500% for PFOA and PFOS isomers, respectively, using a DMS carrier gas composed of 50:50% He:N2 by volume compared to 100% N2, which was crucial in the separation of PFAS isomers under these conditions. Linear, secondary-branched, and tertiary-branched isomers of PFOA and PFOS including those that differ by the position of a single perfluoromethyl group can be resolved by DMS-MS. The DMS compensation field required to transmit different isomers increases as the extent of branching increases. For isomeric PFASs with a single branching point, the compensation field for optimal transmission also increases as the perfluoromethyl group is positioned closer to the carboxylate and sulfonate groups under these conditions. These results indicate that high-resolution DMS-MS should be a useful approach for the rapid analysis of isomeric PFAS.

A microscale solid-phase microextraction probe for the in situ analysis of perfluoroalkyl substances and lipids in biological tissues using mass spectrometry.

The simultaneous analysis of perfluoroalkyl substances (PFASs) and lipids in biological tissues is of importance, especially for in situ and microscale analysis, because it provides significant information to understand the relevance of content, composition, and distribution of lipids to the bioaccumulation of PFASs as well as lipid metabolism affected by the biotoxicity of PFASs. In this study, we report the development of a novel ambient mass spectrometry method for the rapid, in situ, and microscale analysis of PFASs and lipids simultaneously in biological tissues for the investigation of their biological correlation. A microscale solid-phase microextraction (SPME) probe with a probe-end diameter of several-μm was employed for in situ and microscale sampling of biological tissues after PFAS exposure. The SPME probe showed a desirable capacity for the enrichment of PFASs and lipid species simultaneously. After sampling and extraction, the loaded SPME probe was directly applied for nanoESI-MS analysis under ambient and open-air conditions. A high-resolution Fourier transform ion cyclotron resonance (FTICR) mass spectrometer operated in the field-induced mode was introduced to record mass spectra using fast polarity switching between positive and negative ion detection. Most of the lipid species were recorded in the positive ion mass spectrum, and PFASs were recorded in the negative ion mass spectrum. By using the developed method, the in situ analysis of PFASs and lipids in the muscle, brain, heart, kidney, liver, and intestine of zebrafish was realized. In addition, simultaneously imaging PFASs and lipids in individual Daphnia magna was successfully achieved for the investigation of their biological correlation.