Advances in the sample preparation of brominated flame retardants and other brominated compounds

Analytical challenges and opportunities in the study of endocrine disrupting chemicals within an exposomics framework

Exposomics aims to measure human exposures throughout the lifespan and the changes they produce in the human body. Exposome-scale studies have significant potential to understand the interplay of environmental factors with complex multifactorial diseases widespread in our society and whose origin remain unclear. In this framework, the study of the chemical exposome aims to cover all chemical exposures and their effects in human health but, today, this goal still seems unfeasible or at least very challenging, which makes the exposome for now only a concept. Furthermore, the study of the chemical exposome faces several methodological challenges such as moving from specific targeted methodologies towards high-throughput multitargeted and non-targeted approaches, guaranteeing the availability and quality of biological samples to obtain quality analytical data, standardization of applied analytical methodologies, as well as the statistical assignment of increasingly complex datasets, or the identification of (un)known analytes. This review discusses the various steps involved in applying the exposome concept from an analytical perspective. It provides an overview of the wide variety of existing analytical methods and instruments, highlighting their complementarity to develop combined analytical strategies to advance towards the chemical exposome characterization. In addition, this review focuses on endocrine disrupting chemicals (EDCs) to show how studying even a minor part of the chemical exposome represents a great challenge. Analytical strategies applied in an exposomics context have shown great potential to elucidate the role of EDCs in health outcomes. However, translating innovative methods into etiological research and chemical risk assessment will require a multidisciplinary effort. Unlike other review articles focused on exposomics, this review offers a holistic view from the perspective of analytical chemistry and discuss the entire analytical workflow to finally obtain valuable results.

Non-targeted analysis of lipidic extracts by high-resolution mass spectrometry to characterise the chemical exposome: Comparison of four clean-up strategies applied to egg

Biota samples are used to monitor chemical stressors and their impact on the ecosystem and to describe dietary chemical exposure. These complex matrices require an extraction step followed by clean-up to avoid damaging sensitive analytical instruments based on chromatography coupled to mass spectrometry. While interest for non-targeted analysis (NTA) is increasing, there is no versatile or generic sample preparation for a wide range of contaminants suitable for a diversity of biotic matrices. Among the contaminants' variety, persistent contaminants are mostly hydrophobic (mid- to non-polar) and bio-magnify through the lipidic fraction. During their extraction, lipids are generally co-extracted, which may cause matrix effect during the analysis such as hindering the acquired signal. The aim of this study was to evaluate the efficacy of four clean-up methods to selectively remove lipids from extracts prior to NTA. We evaluated (i) gel permeation chromatography (GPC), (ii) Captiva EMR-lipid cartridge (EMR), (iii) sulphuric acid degradation (H2SO4) and (iv) polydimethyl siloxane (PDMS) for their efficiency to remove lipids from hen egg extracts. Gas and liquid chromatography coupled with high-resolution mass spectrometry fitted with either electron ionisation or electrospray ionisation sources operating in positive and negative modes were used to determine the performances of the clean-up methods. A set of 102 chemicals with a wide range of physico-chemical properties that covers the chemical space of mid- to non-polar contaminants, was used to assess and compare recoveries and matrix effects. Matrix effects, that could hinder the mass spectrometer signal, were lower for extracts cleaned-up with H2SO4 than for the ones cleaned-up with PDMS, EMR and GPC. The recoveries were satisfactory for both GPC and EMR while those determined for PDMS and H2SO4 were low due to poor partitioning and degradation/dissociation of the compounds, respectively. The choice of the clean-up methods, among those assessed, should be a compromise that takes into account the matrix under consideration, the levels and the physico-chemical properties of the contaminants.

A cleanup method of serum extracts with molecular sieves as SPE sorbents for the analysis of polybrominated diphenyl ethers

Based on the size- and shape-selective sorption, 13X molecular sieves were developed as solid-phase extraction adsorbents to cleanup serum extract for the determination of polybrominated diphenyl ethers. The important parameters affecting the cleanup efficiency were investigated, including the amount of sorbents, the type and volume of solvents. Under the optimized conditions, the capacity for removing impurities was evaluated via gel permeation chromatography and GC-MS. The results demonstrated that up to 99% of lipids in corn oil (13 mg) can be removed after cleanup, and endogenous compounds in serum can also be effectively eliminated. The cleanup efficiency is not only superior to Hydrophile-Lipophile Balance column, but also close to acid silica gel and multi-function impurity sorbents. Generally, the developed cleanup method exhibited higher recovery for polybrominated diphenyl ethers with more than four bromines, especially for nona- and deca-brominated diphenyl ethers (99.1-117.8%). The cleanup method can be coupled with GC-MS/MS for polybrominated diphenyl ethers analysis in human serum. The method detection limits were 0.01-0.27 ng/mL and average recovery was 50.9-113.3%, except 2,3',4',6-tetrabrominated, 2,3',4,4',6-pentabrominated and 2,3,3',4,4',5',6-heptabrominated diphenyl ethers. 2,2',4,5'-tetrabrominated diphenyl ethers had the highest detection frequency (95%) in human serum, whereas decabrominated diphenyl ethers had the maximum mean concentration (0.50 ng/mL). This article is protected by copyright. All rights reserved.

Review of the environmental occurrence, analytical techniques, degradation and toxicity of TBBPA and its derivatives

BFRs (brominated flame retardants) are a class of compounds that are added to or applied to polymeric materials to avoid or reduce the spread of fire. Tetrabromobisphenol A (TBBPA) is one of the known BFR used many in industries today. Due to its wide application as an additive flame retardant in commodities, TBBPA has become a common indoor contaminant. Recent researches have raised concerns about the possible hazardous effect of exposure to TBBPA and its derivatives in humans and wildlife. This review gives a thorough assessment of the literature on TBBPA and its derivatives, as well as environmental levels and human exposure. Several analytical techniques/methods have been developed for sensitive and accurate analysis of TBBPA and its derivatives in different compartments. These chemicals have been detected in practically every environmental compartment globally, making them a ubiquitous pollutant. TBBPA may be subject to adsorption, biological degradation or photolysis, photolysis after being released into the environment. Treatment of TBBPA-containing waste, as well as manufacturing and usage regulations, can limit the release of these chemicals to the environment and the health hazards associated with its exposure. Several methods have been successfully employed for the treatment of TBBPA including but not limited to adsorption, ozonation, oxidation and anaerobic degradation. Previous studies have shown that TBBPA and its derivative cause a lot of toxic effects. Diet and dust ingestion and have been identified as the main routes of TBBPA exposure in the general population, according to human exposure studies. Toddlers are more vulnerable than adults to be exposed to indoor dust through inadvertent ingestion. Furthermore, TBBP-A exposure can occur during pregnancy and through breast milk. This review will go a long way in closing up the knowledge gap on the silent and over ignored deadly effects of TBBPA and its derivatives and their attendant consequences.

Accumulation of PBDEs and MeO-PBDEs in notothenioid fish from the South Shetland Islands, Antarctica: An interspecies comparative study

Concentrations of polybrominated diphenyl ethers (PBDEs) and methoxylated polybrominated diphenyl ethers (MeO-PBDEs); are reported in specimens of fish notothenioids Chaenocephalus aceratus (SSI), Trematomus bernacchii (ERN), and Nototheniops nudifrons (NOD) from the South Shetland Islands, Antarctica. Significant differences in the accumulation of 2'-MeO-BDE-68 and 6-MeO-BDE-47 were detected among the analysed species. MeO-BDEs were significantly higher in SSI (11.7, 8.6, and 14.1 ng g^-1 lw) than in NOD (1.63, 1.63, and 3.0 ng g^-1 lw) in muscle, liver, and gill, respectively. Feeding ecology traits explain the accumulation patterns of MeO-PBDEs. SSI has a higher feeding activity with a broader diet, followed by ERN, whereas NOD is a benthic/sedentary fish with a narrower diet. The accumulation of PBDEs was neither species-, nor tissue-specific. The current study expands the knowledge concerning the accumulation of PBDEs and MeO-PBDEs in Antarctic marine fish and supports the importance of species-specificity in the accumulation of MeO-PBDEs.

Organophosphate flame retardants in the indoor and outdoor dust and gas-phase of Alexandria, Egypt

Little is known about the presence of organophosphate flame retardants (OPFRs) as a substitute for polybrominated diphenyl ethers in developing countries. This study investigated - for the first time - concentrations, sources and exposure levels of OPFRs in the indoor and outdoor environments of Alexandria, Egypt, in dust and gas-phase samples. Passive samplers were deployed (n = 78) to determine gaseous concentrations, and various dust samples were collected from apartments (n = 25), working places (n = 14), cars (n = 18), and outdoors (OD, n = 30). Indoor concentrations (air: 7.0-64 pg/m³; dust: 150-1850 ng/g) were significantly higher than outdoor (2.0-16 pg/m³ and 83-475 ng/g) concentrations. Tris-1,3-dichloropropyl phosphate (TDCIPP), tris(1-chloro-2-propyl) phosphate (TCIPP), tri (2-butoxyethyl) phosphate (TBOEP) and triphenyl phosphate (TPHP) dominated in all samples with more indoor variabilities. Profiles of OPFRs in OD and floor dust (collected from carpets and floors) were similar but differed from elevated fine dust (collected 1 m above the floor from all available surfaces), possibly due to the influence of carryover of OD by shoes. Despite the high uncertainty in dust - air partitioning coefficients, log transformed values showed significant linear relationships with log octanol - air-partitioning coefficients in all microenvironments, indicating an equilibrium partitioning between dust and vapor. Exposure assessment indicated the importance of the dermal exposure route for adults and ingestion route for children.

Selected organohalogenated flame retardants in Egyptian indoor and outdoor environments: Levels, sources and implications for human exposure

There is scant information on the presence of the polybrominated diphenyl ethers (PBDEs) and other alternative flame-retardants (NFRs) in Africa. Hence, to investigate their levels, sources, and human exposure scenarios, elevated fine dust (EFD) samples from apartments (n = 12), working places (n = 9) and cars (n = 12), floor dust (FD) samples (n = 5) and outdoor dust samples (n = 21) were collected from Alexandria, Egypt, during 2014. Gaseous concentrations were estimated using low density polyethylene sheets (n = 33 and 21 for indoor and outdoor sites, respectively). Indoor gaseous and dust PBDE (7.0-300 pg/m³; 4.0-770 ng/g), and NFR (0.40-48 pg/m³; 0.50-8.5 ng/g) concentrations were significantly higher (p = 0.004-0.02) than outdoor concentrations (PBDEs: 3.0-41 pg/m³, 1.5-195 ng/g; NFRs: 0.20-13 pg/m³, 0.50-4.0 ng/g). Median PBDE concentration in cars (210 ng/g) was higher than in apartments and working places (130  ng/g respectively). PBDE concentrations in FD were 7.0-14-folds lower than EFD concentrations. Outdoor PBDE concentrations were significantly higher (p < 0.01) at residential-industrial places with older buildings. All samples were dominated by BDE-47 and 99. HBB, BTBPE and DDC-CO were the most abundant NFRs in EFD samples. Profiles of PBDE and NFR in FD closely matched those of outdoor dust, indicating a possible carryover from the outdoor environment. Although factors such as number of electronics, construction year and floor type significantly correlated with the majority of PBDE congeners and some NFRs in apartments and working places, sources were not clearly identified for NFRs. Significant log-linear relationships were obtained between theoretical and calculated dust-air partitioning coefficients for all samples indicating an equilibrium state between dust and vapor. Low possibility of occurrence of adverse health effects was concluded, with the inhalation pathway (for adults) and dust ingestion (for children) acting as the most important exposure routes.

Critical review of the analysis of brominated flame retardants and their environmental levels in Africa

World-wide, the prevalence of brominated flame retardants (BFRs) is well documented for routine analysis of environmental and biological matrices. There is, however, limited information on these compounds in the African environment and insufficient information on the analytical approaches used to obtain data. This paper presents a review on BFR levels in the African environment and the various analytical methodologies specifically applied in Africa for polybrominated diphenyl ethers (PBDEs), polybrominated biphenyls and alternative-BFRs. The analyses include liquid sample preparation using liquid-liquid and solid phase extraction and solid sample preparation involving Soxhlet extraction, with ultrasound-assisted extraction increasingly being applied. Instrumental detection techniques were limited to gas chromatography coupled with electron capture detector and electron impact ionisation with single quadrupole mass spectrometers. Information on congener profile prevalence in indoor dust, soil, aquatic environment (water, sediment, and aquatic organisms), eggs, wastewater treatment plant compartments, landfills (leachate and sediment) and breast milk are presented. Although PBDEs were inconsistently detected, contamination was reported for all investigated matrices in the African environment. The manifestation in remote regions indicates the ubiquitous prevalence and long-range transport of these compounds. Levels in sediment, and breast milk from some African countries were higher than reported for Asia and Europe. Due to limited data or non-detection of alternative-BFRs, it is unclear whether banned formulations were replaced in Africa. Most of the data reported for BFR levels in Africa were obtained in non-African laboratories or in South Africa and formed the basis for our discussion of reported contamination levels and related methodologies.

Fabric phase sorptive extraction: Two practical sample pretreatment techniques for brominated flame retardants in water

Sample pretreatment is the critical section for residue monitoring of hazardous pollutants. In this paper, using the cellulose fabric as host matrix, three extraction sorbents such as poly (tetrahydrofuran) (PTHF), poly (ethylene glycol) (PEG) and poly (dimethyldiphenylsiloxane) (PDMDPS), were prepared on the surface of the cellulose fabric. Two practical extraction techniques including stir bar fabric phase sorptive extraction (stir bar-FPSE) and magnetic stir fabric phase sorptive extraction (magnetic stir-FPSE) have been designed, which allow stirring of fabric phase sorbent during the whole extraction process. In the meantime, three brominated flame retardants (BFRs) [tetrabromobisphenol A (TBBPA), tetrabromobisphenol A bisallylether (TBBPA-BAE), tetrabromobisphenol A bis(2,3-dibromopropyl)ether (TBBPA-BDBPE)] in the water sample were selected as model analytes for the practical evaluation of the proposed two techniques using high-performance liquid chromatography (HPLC). Moreover, various experimental conditions affecting extraction process such as the type of fabric phase, extraction time, the amount of salt and elution conditions were also investigated. Due to the large sorbent loading capacity and unique stirring performance, both techniques possessed high extraction capability and fast extraction equilibrium. Under the optimized conditions, high recoveries (90-99%) and low limits of detection (LODs) (0.01-0.05 μg L(-1)) were achieved. In addition, the reproducibility was obtained by evaluating the intraday and interday precisions with relative standard deviations (RSDs) less than 5.1% and 6.8%, respectively. The results indicated that two pretreatment techniques were promising and practical for monitoring of hazardous pollutants in the water sample. Due to low solvent consumption and high repeated use performance, proposed techniques also could meet green analytical criteria.

Environmental occurrence, analysis and human exposure to the flame retardant tetrabromobisphenol-A (TBBP-A)-A review

TBBP-A is a high production volume chemical applied widely as a flame retardant in printed circuit boards. Recent studies have raised concern over potential harmful implications of TBBP-A exposure in human and wildlife, leading to its classification under group 2A "Probably carcinogenic to humans" by the International Agency for Research on Cancer. This article provides a comprehensive review of the available literature on TBBP-A analysis, environmental levels and human exposure. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been identified as the method of choice for robust, accurate and sensitive analysis of TBBP-A in different matrices. TBBP-A has been detected in almost all environmental compartments all over the world, rendering it a ubiquitous contaminant. Human exposure studies revealed dust ingestion and diet as the major pathways of TBBP-A exposure in the general population. Toddlers are likely to be more exposed than adults via accidental indoor dust ingestion. Moreover, exposure to TBBP-A may occur prenatally and via breast milk. There are no current restrictions on the production of TBBP-A in the EU or worldwide. However, more research is required to characterise human exposure to TBBP-A in and around production facilities, as well as in e-waste recycling regions.

Vortex-homogenized matrix solid-phase dispersion coupled with gas chromatography – electron-capture negative-ion mass spectrometry to determine halogenated phenolic compounds in seafood

This work represents the development of vortex-homogenized matrix solid-phase dispersion (VH-MSPD) as an effective and simple method to rapidly extract halogenated phenolic compounds in marketed seafood samples.

State of the art of environmentally friendly sample preparation approaches for determination of PBDEs and metabolites in environmental and biological samples: A critical review

Green chemistry principles for developing methodologies have gained attention in analytical chemistry in recent decades. A growing number of analytical techniques have been proposed for determination of organic persistent pollutants in environmental and biological samples. In this light, the current review aims to present state-of-the-art sample preparation approaches based on green analytical principles proposed for the determination of polybrominated diphenyl ethers (PBDEs) and metabolites (OH-PBDEs and MeO-PBDEs) in environmental and biological samples. Approaches to lower the solvent consumption and accelerate the extraction, such as pressurized liquid extraction, microwave-assisted extraction, and ultrasound-assisted extraction, are discussed in this review. Special attention is paid to miniaturized sample preparation methodologies and strategies proposed to reduce organic solvent consumption. Additionally, extraction techniques based on alternative solvents (surfactants, supercritical fluids, or ionic liquids) are also commented in this work, even though these are scarcely used for determination of PBDEs. In addition to liquid-based extraction techniques, solid-based analytical techniques are also addressed. The development of greener, faster and simpler sample preparation approaches has increased in recent years (2003-2013). Among green extraction techniques, those based on the liquid phase predominate over those based on the solid phase (71% vs. 29%, respectively). For solid samples, solvent assisted extraction techniques are preferred for leaching of PBDEs, and liquid phase microextraction techniques are mostly used for liquid samples. Likewise, green characteristics of the instrumental analysis used after the extraction and clean-up steps are briefly discussed.

Brominated flame retardants and seafood safety: a review

Brominated flame retardants (BFRs), frequently applied to industrial and household products to make them less flammable, are highly persistent in the environment and cause multi-organ toxicity in human and wildlife. Based on the review of BFRs presence in seafood published from 2004 to 2014, it is clear that such pollutants are not ideally controlled as the surveys are too restricted, legislation inexistent for some classes, the analytical methodologies diversified, and several factors as food processing and eating habits are generally overlooked. Indeed, while a seafood rich diet presents plenty of nutritional benefits, it can also represent a potential source of these environmental contaminants. Since recent studies have shown that dietary intake constitutes a main route of human exposure to BFRs, it is of major importance to review and enhance these features, since seafood constitutes a chief pathway for human exposure and biomagnification of priority environmental contaminants. In particular, more objective studies focused on the variability factors behind contamination levels, and subsequent human exposure, are necessary to support the necessity for more restricted legislation worldwide.

Advances in Instrumental Analysis of Brominated Flame Retardants: Current Status and Future Perspectives

This review aims to highlight the recent advances and methodological improvements in instrumental techniques applied for the analysis of different brominated flame retardants (BFRs). The literature search strategy was based on the recent analytical reviews published on BFRs. The main selection criteria involved the successful development and application of analytical methods for determination of the target compounds in various environmental matrices. Different factors affecting chromatographic separation and mass spectrometric detection of brominated analytes were evaluated and discussed. Techniques using advanced instrumentation to achieve outstanding results in quantification of different BFRs and their metabolites/degradation products were highlighted. Finally, research gaps in the field of BFR analysis were identified and recommendations for future research were proposed.

A one-step extraction/clean-up method for determination of PCBs, PBDEs and HBCDs in environmental solid matrices

A selective pressurized liquid extraction (S-PLE) method was developed for rapid determination of 3 classes of halogenated organic contaminants in indoor dust, soil and sediment samples. The optimised method used 3 : 2 v/v n-hexane-dichloromethane for extraction of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDs). Extraction was performed at 90 °C for 5 min followed by 4 min static time under 1500 psi. Good recoveries of target analytes were obtained after 3 extraction cycles. In-cell cleanup was performed using 10 g of 44% H2SO4 acid silica and 5 g of florisil (secondary fat retainer), while copper powder was used to remove elemental sulfur. The method was validated using NIST SRM2585 and SRM 1941b in addition to an in-house previously characterised soil sample. Measured concentrations of target compounds showed good agreement with the certified values with RSD < 20% indicating the good accuracy and precision of the S-PLE method. Clean extracts provided low noise levels resulting in low method detection limits (<0.03 ng g(-1)) and LOQs (<0.1 ng g(-1)). The method developed was applied successfully to real environmental samples and it provided various advantages over traditional methods including reduced solvent consumption and analysis time, minimal sample contamination and high sample throughput which can be beneficial for environmental monitoring programs dealing with large numbers of samples.