Determination of perfluorinated compounds in aquatic organisms: a review

Bioaccumulation of PFAS in aquatic organisms is an environmental problem of growing concern around the world. This problem has been tackled by regulatory bodies by proposing EQS for biota in EU water bodies and tolerable daily intake for food. The introduction of regulatory limits requires the availability of harmonised and validated analytical methods of sufficient sensitivity. This paper reviews recent advances in analytical methods for analysis of PFAS in aquatic organisms. The methods available for biota analysis are mostly based on three extraction procedures: ion-pair extraction, solvent liquid extraction, and alkaline digestion. The resulting extracts are then subjected to different clean-up or enrichment steps on solid adsorbents, for example graphitized carbon black, C₁₈, and WAX phases. All methods reviewed in this work give reliable results but are partially validated only, because of the lack of certified reference materials and regular interlaboratory exercises. The few interlaboratory exercises performed on real unspiked samples did not afford satisfactory results for PFAS other than PFOS, especially for matrices with high lipid content, for example mussels. The reasons for those partially negative results have been identified, and can mainly be attributed to calibration procedures and availability and purity of standards. The urgent need for certified reference materials for this type of analysis is emphasized.     

Mass spectral studies towards more reliable measurement of perfluorooctanesulfonic acid and other perfluorinated chemicals (PFCs) in food matrices using liquid chromatography/tandem mass spectrometry

Liquid chromatography/mass spectrometry (LC/MS) experiments are described, leading to a reliable method for the measurement of perfluorooctanesulfonic acid (PFOS) and other perfluorinated chemicals (PFCs) in foods. Separations were performed on new fluorinated stationary phases, RP Octyl (‐C₈F₁₇) or propyl‐perfluorobenzene (‐C₃H₆‐C₆F₅), to ensure resolution of PFOS and interfering taurohydroxycholate isomers. Aqueous ammonium formate (5 mM) and methanol were used as the mobile phases. The mass spectrometer was operated in negative electrospray ionisation mode, recording two transitions for each analyte and one for each internal standard. The purities of the analytical standards for the eleven target perfluoro analytes (C₇ to C₁₂ carboxylic acids, C₄, C₆ and C₈ sulfonic acids, and octanesulfonamide (PFOSA)) were found to be in close agreement with the supplied values; the lowest purity was 91%. Five candidate internal standards were investigated, ¹³C₄‐PFOS, ¹³C₄‐perfluorooctanoic acid, ¹³C₂‐perfluorodecanoic acid, D₉‐n‐ethylperfluorooctanesulfonamidoethanol (D₉‐n‐Et‐FOSE) and D₃‐n‐methylperfluorooctanesulfonamide (D₃‐n‐Me‐FOSA); the purities were all >98%. The use of tetrahydro‐PFOS generated backgrounds (>1 µg/kg) for perfluoroheptanoic acid and perfluorobutanesulfonic acid. Similarly D₉‐n‐Et‐FOSE was unacceptable and D₃‐n‐Me‐FOSA was volatile, leaving no clear candidate for normalisation of the measurement of PFOSA. Severe matrix‐induced suppression and enhancement effects influenced ionisation, making external calibration and quantification problematic. This was addressed by a parallel standard addition and matrix‐matching approach, comparing ionisation in methanol, in procedural blanks and in food‐based extracts. The limits of detection (LODs) of 0.001–0.01 µg/kg in solvent and 0.01–1 µg/kg in foods demonstrate that this method is suitable for the determination of PFCs in all food to the required 1 µg/kg reporting level. © Crown copyright 2009. Reproduced with the permission of Her Majesty's Stationery Office. Published by John Wiley & Sons, Ltd.     

Radiolysis of selected antibiotics and their toxic effects on various aquatic organisms

This study was conducted to investigate the decomposition of three γ-irradiated antibiotics (e.g., tetracycline, sulfamethazine, and lincomycin) and to compare the toxic effects on Daphnia magna, Vibrio fischeri, and Pseudokirchneriella subcapitata. The median cell growth inhibition concentrations (IC₅₀) of tetracycline, lincomycin, and sulfamethazine for P. subcapitata dramatically increased (e.g., toxicity decreased) after radiolysis. The results demonstrated that γ-radiation treatment was efficient to decompose antibiotics and thereby their toxicity on P. subcaptitata remarkably decreased due to reduced parent compounds.     

一些全氟(及多氟)有机化合物蒸汽压的QSPR研究

全氟(及多氟)化合物(PFCs)是环境中普遍存在的新一类持久性有机污染物。对其中有蒸汽压数据的35个全氟(及多氟)化合物进行了HF/6-31G*水平上的结构优化,并在优化结构的基础上进行分子表面静电势及其导出参数的计算。分别用"留一法"交叉验证及外部测试集对模型进行检验。结果表明,分子表面静电势参数结合分子表面积可以很好地表达全氟(及多氟)化合物与其分子结构间的定量关系,所建立的QSPR模型具有较强的稳健性和预测能力,同时也证明了分子静电势在全氟化合物QSPR研究中的适用性。     

Predicting the biodegradation products of perfluorinated chemicals using CATABOL

Perfluorinated chemicals (PFCs) form a special category of organofluorine compounds with particularly useful and unique properties. Their large use over the past decades increased the interest in the study of their environmental fate. Fluorocarbons may have direct or indirect environmental impact through the products of their decomposition in the environment. It is a common knowledge that biodegradation is restricted within non-perfluorinated part of molecules: however, a number of studies showed that defluorination can readily occur during biotransformation. To evaluate the fate of PFCs in the environment a set of principal transformations was developed and implemented in the simulator of microbial degradation using the catabolite software engine (CATABOL). The simulator was used to generate metabolic pathways for 171 perfluorinated substances on Canada's domestic substances list. It was found that although the extent of biodegradation of parent compounds could reach 60%, persistent metabolites could be formed in significant quantities. During the microbial degradation a trend was observed where PFCs are transformed to more bioaccumulative and more toxic products. Perfluorooctanoic acid and perfluorooctanesulfonate were predicted to be the persistent biodegradation products of 17 and 27% of the perfluorinated sulphonic acid and carboxylic acid containing compounds, respectively.     

Analysis of perfluorinated chemicals in sludge: Method development and initial results

A fast, rigorous method was developed to maximize the extraction efficacy for ten perfluorocarboxylic acids and perfluorooctanesulfonate from waste-water-treatment sludge and to quantitate using liquid chromatography, tandem-mass spectrometry (LC/MS/MS). First, organic solvents were tested for extraction efficiency, including acetonitrile (ACN), methanol (MeOH), isopropanol (IPA), tetrahydrofuran (THF), and 50/50 ACN/MeOH (v/v). Among the extractants tested, 50/50 ACN/MeOH yielded the best results for our combined criteria of extraction efficacy and solvent-handling convenience. Second, chemical pretreatment prior to solvent extraction was tested with sodium hydroxide (NaOH), potassium hydroxide (KOH), hydrochloric acid (HCl), and potassium persulfate (K₂S₂O₈). Pretreatment with NaOH and HCl effectively recovered additional PFCs from the sludge, but KOH and K₂S₂O₈ digestion were less effective than no pretreatment. Third, cleanup methods were investigated with solid-phase extraction using HLB (hydrophilic–lipophilic balanced) and WAX (weak-anion exchange) stationary phases, and with ion-pairing. The HLB stationary phase yielded a slight edge over the other two cleanup strategies in terms of recoverable PFCs and chromatographic separation. Finally, the appropriateness of isotopically labeled PFCs for quantitating unlabeled PFCs using isotopic dilution in complex sludge extracts was evaluated by comparison to results obtained with the standard-addition method. A National Institute of Standards and Technology (NIST) domestic sludge (CRM 2781) was analyzed using our finalized method and compared with previously reported results.     

Flow-based in vivo NMR spectroscopy of small aquatic organisms

NMR applied to living organisms is arguably the ultimate tool for understanding environmental stress responses and can provide desperately needed information on toxic mechanisms, synergistic effects, sublethal impacts, recovery, and biotransformation of xenobiotics. To perform in vivo NMR spectroscopy, a flow cell system is required to deliver oxygen and food to the organisms while maintaining optimal line shape for NMR spectroscopy. In this tutorial, two such flow cell systems and their constructions are discussed: (a) a single pump high-volume flow cell design is simple to build and ideal for organisms that do not require feeding (i.e., eggs) and (b) a more advanced low-volume double pump flow cell design that permits feeding, maintains optimal water height for water suppression, improves locking and shimming, and uses only a small recirculating volume, thus reducing the amount of xenobiotic required for testing. In addition, key experimental aspects including isotopic enrichment, water suppression, and 2D experiments for both ¹³C enriched and natural abundance organisms are discussed.     

Accuracy and precision in the determination of perfluorinated chemicals in human blood verified by interlaboratory comparisons

Perfluorinated chemicals (PFCs) are analyzed in laboratories worldwide to determine human blood levels and exposure pathways. The development of the analytical technique has been rapid in the last 10 years, and prerequisites for accurate and precise determination of PFCs in human blood at low ng/g concentrations are today readily available. The main contributing factors are the improved LC–MS instrumentations, the increased availability of native and mass labeled PFC standards, and new column materials available for chromatographic separations. The results of the first international interlaboratory study (ILS) in 2005 on PFCs revealed relatively better analytical results for human blood analyses when compared to analyses of a number of environmental matrices. The representative accuracy for the analyses of PFCs in human matrixes reported in recent years was established in the second human serum ILS in 2006. Interlaboratory standard deviations for the two human serum samples one low level concentration and one medium level concentration were found to be 12% and 16% for PFOS, respectively, and 47% and 21% for PFOA, respectively. Reported detections for all PFCs followed a frequency of PFOS > PFOA > PFHxS > PFNA > PFDA ? PFDoA ? PFDS ? PFHxA. Due to the small number of reported values for the other perfluorosulfonates and perfluorocarboxylates, standard deviations were not established.     

Ecotoxicological modelling of cosmetics for aquatic organisms: A QSTR approach

In this study, externally validated quantitative structure–toxicity relationship (QSTR) models were developed for toxicity of cosmetic ingredients on three different ecotoxicologically relevant organisms, namely Pseudokirchneriella subcapitata, Daphnia magna and Pimephales promelas following the OECD guidelines. The final models were developed by partial least squares (PLS) regression technique, which is more robust than multiple linear regression. The obtained model for P. subcapitata shows that molecular size and complexity have significant impacts on the toxicity of cosmetics. In case of P. promelas and D. magna, we found that the largest contribution to the toxicity was shown by hydrophobicity and van der Waals surface area, respectively. All models were validated using both internal and test compounds employing multiple strategies. For each QSTR model, applicability domain studies were also performed using the “Distance to Model in X-space” method. A comparison was made with the ECOSAR predictions in order to prove the good predictive performances of our developed models. Finally, individual models were applied to predict toxicity for an external set of 596 personal care products having no experimental data for at least one of the endpoints, and the compounds were ranked based on a decreasing order of toxicity using a scaling approach.     

An evaluation of the HPLC-Gel chromatographic method for analyzing metallothioneins in aquatic organisms

The use of high-performance liquid chromatography to determine the concentrations of metal-binding proteins (MBP) in freshwater mussels has been evaluated. Initial use of dilute buffers (e.g., 1OmM TRIS, pH 7 or 8), to minimize competition between the buffer and the metal-cytosolic ligand complexes, proved unacceptable; high losses of low molecular weight marker proteins occurred during chromatographic separation, presumably as a result of adsorption to the gel-permeation column packing. Losses were more dependent on salt than pH; satisfactory recoveries were obtained in the pH range 6-8 with 1OmM buffer solutions and 100mM added electrolyte (NACl; KCl). Competition experiments performed with commercial metallothionein (pre-labelled with (109)Cd) and fresh mussel cytosol extract demonstrated that no appreciable metal exchange occurred during the 20-min pre-equilibration or the subsequent chromatographic separation step. With (203)Hg-labelled metallothionein occasional losses were noted, however, appreciable loss of the radioisotope ranging from 50 to 58% did occur with (65)Zn-labelled metallothionein during the chromatographic separation step. These results, particularly for Zn indicate that the recovery of metals after separation using this chromatographic method may vary, even for metals sharing similar chemical properties.     

Heterocyclic compounds of marine organisms (review)

The literature data on heterocyclic compounds of marine organisms are systematized. Chief attention is directed to physiologically active substances.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 435–452, April, 1977.     

Pheromones, attractants and other chemical cues of aquatic organisms and amphibians

This review covers the subject of pheromones, attractants and other chemical cues of aquatic invertebrates, fishes and amphibians (including salamanders and anurans). Major topics include the sex pheromones of gastropods, salamanders and a giant tree frog, and the conspecific attraction of sperm to ova of some of the organisms and animals described in this review.     

Properties of block (co)polymers of methyl methacrylate and perfluorinated polyphenylenegermane

Hybrid (co)polymers of linear-dendritic structure were prepared by radical polymerization of methyl methacrylate in the presence of superbranched perfluorinated polyphenylenegermane to high conversions. The molecular-weight characteristics and the sorption capacity of the products were examined. The glass transition point, elastic modulus, mechanical loss factor, and tensile strength of the copolymers obtained were determined.     

ω-(2-benzimidazolyl)perfluorinated carboxylic acids and their derivatives

A convenient method is proposed for the preparation of -(2-benzimidazolyl) perfluorinated carboxylic acids and their amides by condensation of o-phenylenediamine with imides of perfluorinated dicarboxylic acids. The transformations of the o-aminoanilides of the amides of the perfluorinated dicarboxylic acids were studied by thermal analysis and mass spectroscopy.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1262–1265, September, 1976.     

Micellization in solutions of hybrid block copolymer of poly(methyl methacrylate) and hyperbranched perfluorinated poly(phenylene germane)

Fractions of the product resulting from the polymerization of methyl methacrylate in the presence of hyperbranched perfluorinated poly(phenylene germane) have been studied by dynamic and static light scattering and capillary viscometry in methyl ethyl ketone solutions. The hybrid product is obtained via the reaction of the chain transfer of methyl methacrylate propagating radicals to pentafluorophenyl groups. Eight fractions have been isolated by fractional precipitation, including fractions of the linear-dendrite block copolymer. Light scattering studies have shown that hybrid macromolecules containing 15–20 wt % hyper-branched fragments form micelles in solutions.     

Cr(III) or Ce(IV) impregnated perfluorinated resin-sulfonic acid catalyst for the oxidation of alcohols

Several polymer supported catalysts are prepared by treatment of Nafion® 511 (abbreviated as NAFK below) with metal salts and found to be effective in promoting the dehydrogenative oxidation of alcohols with ^tBuOOH.     

Analysis of ultratrace triorganotin compounds in aquatic organisms by using capillary electrophoresis-inductively coupled plasma mass spectrometry

A microwave-assisted extraction used to extract trace triorganotin from aquatic organisms and a sensitive analytical method for the determination of ultratrace triorganotin (namely trimethyltin, triethyltin, tripropyltin and tributyltin) with capillary electrophoresis-inductively coupled plasma mass spectrometry were firstly described in this study. The extraction method is simple, effective and can be used to extract trace triorganotin in aquatic organisms within several min. The analytical method has a much lower detection limit of 0.2-0.7 ng Sn/mL for triorganotin compounds, and can be used to determine trace triorganotin in aquatic organisms directly without any derivatization and preconcentration. Using above methods, we have successfully determined trimethyltin, triethyltin, tripropyltin and tributyltin in dried Mya arenaria Linnaeus and Corbicula fluminea within 17 min with a recovery of 93-104% and a RSD (relative standard deviation, n = 6) of 2-5%. Our results showed that dried M. arenaria Linnaeus contained an extremely high tributyltin of 5.1 μg Sn/g dried weight, indicating that it may be a good biomarker for the organotin pollution in ocean.     

Determination by MS-MS of 1,1-dichlorodimethyl sulfone from pulp mill bleach plant effluents in aquatic organisms

Gas chromatography (GC) with electron capture detection (ECD), GC combined with mass spectrometry (MS), GC with multi-stage mass spectometry (MS-MS), and direct inlet MS-MS have been used to determine 1,1-dichlorodimethyl sulfone (DDS) in aquatic organisms in the receiving waters outside a pulp mill bleach plant. Both GC-MS-MC and direct inlet MS-MS of tissue extracts of fish and mussel appear to be sensitive, selective, and rapid analytical techniques for the determination of DDS.