Comprehensive two-dimensional gas chromatography of polybrominated diphenyl ethers

Comprehensive two-dimensional gas chromatography with micro electron-capture detection (GCxGC-muECD) was evaluated for the separation of 125 polybrominated diphenyl ethers (PBDEs). From among the six column combinations that were evaluated, DB-1x007-65HT was found to be the most suitable because of: (i) the highest number of BDE congeners separated; (ii) the least decomposition of higher brominated congeners; and (iii) the most suitable maximum operating temperature. The separation of the 125 BDE congeners from five hydroxy- and two methoxy-BDEs and nine other brominated flame retardants (polybrominated biphenyls, tetrabromobisphenol-A, methyl-tetrabromobisphenol-A and hexabromocyclododecane) was also studied. Fluorinated BDEs were found to be valuable internal standards for the determination of BDEs because of their very similar physico-chemical properties and excellent separation from the parent BDEs, mainly in the second dimension. GCxGC-time-of-flight MS and GCxGC-muECD were shown to be useful tools to identify decomposition products of nona- and deca-substituted BDEs, which are formed during the GC run. Three nona-BDEs were shown to be the major decomposition products of BDE 209.     

Improved GC/ECNI-MS sensitivity of decabromodiphenyl ether determination on 30 m columns by increasing the carrier gas flow after a modified gel permeation chromatographic cleanup protocol employing cyclohexane/ethyl acetate as eluent

BDE-209 is the predominant constituent of the commercial mixture decabromodiphenyl ether which is used as brominated flame retardant (BFR). Owing to difficulties associated with the high mass (thermal instability and low vapour pressure), short GC columns (≤15?m) have been suggested for its analysis while longer columns (30–50?m) are suggested for other polybrominated diphenyl ether (PBDE) congeners. To overcome this considerable expenditure in the analysis of PBDEs, we aimed at increasing the sensitivity of BDE-209 analysis by gas chromatography coupled with electron-capture negative ion mass spectrometry (GC/ECNI-MS) on a 30?m column. The chromatographic performance of BDE-209 on the 30?m GC column was improved by increasing the carrier gas flow from initially 1.2?mL?min^?1 to 5 or 10?mL?min^?1 after the last octabromo diphenyl ether (Br₈DE) congener was eluted. With this high carrier gas flow, the column residence time of BDE-209 was shortened by ～25%, the peak height was increased and, consequently, the limit of detection by GC/ECNI-MS in selected ion monitoring (SIM) mode was improved. When this high-flow GC/ECNI-MS-SIM method was applied to a sediment sample, we realized that gel permeation chromatography (GPC) – used for the removal of lipids and/or sulphur – provided low recovery rates for BDE-209. The large molecule BDE-209 eluted late and only 50% was recovered by our previous standard protocol for polyhalogenated compounds. Application of a modified GPC procedure with a longer collection time increased the recovery of BDE-209 in the GPC step to ～90%.     

Environmental analysis of higher brominated diphenyl ethers and decabromodiphenyl ethane

Methods for environmental analysis of higher brominated diphenyl ethers (PBDEs), in particular decabromodiphenyl ether (BDE209), and the recently discovered environmental contaminant decabromodiphenyl ethane (deBDethane) are reviewed. The extensive literature on analysis of BDE209 has identified several critical issues, including contamination of the sample, degradation of the analyte during sample preparation and GC analysis, and the selection of appropriate detection methods and surrogate standards. The limited experience with the analysis of deBDethane suggests that there are many commonalities with BDE209. The experience garnered from the analysis of BDE209 over the last 15 years will greatly facilitate progress in the analysis of deBDethane.     

Controlled pyrolysis of polyethylene/polypropylene/polystyrene mixed plastics with high impact polystyrene containing flame retardant: Effect of decabromo diphenylethane (DDE)

The pyrolysis of polyethylene(PE)/polypropylene(PP)/polystyrene(PS) mixed with high impact polystyrene (HIPS-Br) containing decabromo diphenylethane (DDE) as a brominated flame retardant with antimony trioxide as a synergist was performed under controlled temperature programmed pyrolysis (two steps) conditions to understand the decomposition behaviour and evolution of brominated hydrocarbons from flame-retardant additives. The liquid products were extensively analyzed by gas chromatographs equipped with FID, ECD, MSD, TCD, AED and FT-IR. The solid residue samples were analyzed by powder X-ray diffraction and combustion followed by ion-chromatography. The controlled pyrolysis of PE/PP/PS/HIPS-Br significantly affected the decomposition behaviour of HIPS-Br and subsequently the formation of decomposition products. GC/ECD analysis confirmed that the brominated hydrocarbons were concentrated in step 1 liquid products leaving less brominated hydrocarbons in the step 2 liquid products, similar to the decabromo diphenyl ether flame retardant containing mixed plastics. The yield of liquid products in step 1 from 3P/DDE-Sb(5) was 5 wt% and from 3P/DDE-Sb(0) was 2.4 wt%. The presence of antimony in the DDE containing plastics affected the yield of liquid, gas and residue products. ECD analysis showed that the presence of antimony increased the Br containing hydrocarbons and step 1 has 3-4 times higher brominated compounds than step 2 hydrocarbons in both the samples.     

Extraction and determination of polybrominated diphenyl ethers in water and urine samples using solidified floating organic drop microextraction along with high performance liquid chromatography

We have developed a method, termed solidification of floating organic drop microextraction (SFOME), for the extraction of polybrominated diphenyl ethers (PBDEs) in water and urine samples, this followed by quantification via HPLC. This method requires very small quantities of organic solvent consumption. It is based on exposing a floating solidified drop of an organic solvent on the surface of aqueous solution in a sealed vial. The organic drop is easily collected with a spatula, molten (at ambient temperature), and then submitted to HPLC. Experimental parameters including extraction solvent and its volume, disperser solvent and its volume, extraction time, ionic strength, stirring speed and extraction temperature were optimized. The enrichment factors of analytes are in the range from 921 to 1,462, and acceptable extraction recoveries (92%–118%) are obtained. The dynamic linear range for five PBDE congeners is in the range of 0.5–75?μg.L^?1 and from 5 to 500?μg.L^?1 for BDE 209. The correlation coefficients range from 0.9960 to 0.9999. The limits of detection (at S/N?=?3) for PBDE congeners vary between 0.01 and 0.04?μg.L^?1. This method has been successfully applied to detecting PBDEs in two environmental waters and in human urine.

Toxicokinetics and the related metabolites in rainbow trout (Oncorhynchus mykiss) after exposure to decabromodiphenyl ether

Decabromodiphenyl ether (BDE209) is poorly absorbed by mammals, and little information is available on the toxicokinetics of BDE209 and its metabolites in fish. In the present study, rainbow trout (Oncorhynchus mykiss) were administered to 100 ng/g and 500 ng/g body wet weight of BDE209 via a single intraperitoneal injection and parent BDE209 and its metabolites were sequentially monitored for 28 days. The results showed that toxicokinetic profiles of BDE209 could be described by the one-compartment model. In the higher dose group (500 ng/g wet weight), the calculated half-life (t _1/2) and elimination rate (k _e) were 17.7 d and 0.039/d in the liver, and 100.3 d and 0.007/d in the muscle, respectively. Three major methoxylated brominated diphenyl ethers (MeO-BDEs) were detected with 2,2′,4,4′-tetrabromo-5-methoxydiphenyl ether (5-MeO-BDE47) being detected in all tissue samples. There was no significant temporal change of 5-MeO-BDE47 concentration in the muscle, whereas an exponential increase was observed in the liver. Therefore, the metabolism rate of BDE209 depended on the administered dose. BDE209 was hardly accumulated in the muscle of rainbow trout, while the liver was a primary metabolic organ. MeO-BDEs were formed via metabolism of BDE209, which probably played a significant role in fish toxicology as a potential indicator.     

Instrumental methods and challenges in quantifying polybrominated diphenyl ethers in environmental extracts: a review

Increased interest in the fate, transport and toxicity of polybrominated diphenyl ethers (PBDEs) over the past few years has led to a variety of studies reporting different methods of analysis for these persistent organic pollutants. Because PBDEs encompass a range of vapor pressures, molecular weights and degrees of bromine substitution, various analytical methods can lead to discrimination of some PBDE congeners. Recent improvements in injection techniques and mass spectrometer ionization methods have led to a variety of options to determine PBDEs in environmental samples. The purpose of this paper is therefore to review the available literature describing the advantages and disadvantages in choosing an injection technique, gas chromatography column and detector. Additional discussion is given to the challenges in measuring PBDEs, including potential chromatographic interferences and the lack of commercial standards for higher brominated congeners, which provides difficulties in examining degradation and debromination of BDE congeners, particularly for BDE 209.     

DNA aptamers for selective identification and separation of flame retardant chemicals

Polybrominated diphenyl ethers (PBDEs) are group of chemicals which are representative persistent organic pollutants (POPs) and used as brominated flame retardants for many consumer products. PBDEs were phased out since 2009 but are still frequently observed in various environmental matrices and human body. Here, we report ssDNA aptamers which bind to BDE47, one of the PBDE congeners commonly found in various environmental matrices, and show affinity to other major tri-to hepta- BDE congeners. The PBDE specific aptamers were isolated from random library of ssDNA using Mag-SELEX. Two out of 15 sequences, based on their alignment and hairpin loop structures, were chosen to determine dissociation constant with BDE47 and showed from picomolar to nanomolar affinities (200 pM and 1.53 nM). The aptamers displayed high selectivity to the original target, BDE47, and implying general specificity to PBDE backbone with varying affinities to other congeners. Further, we showed that the use of two aptamers together could enhance the separation efficiency of BDE47 and other BDE congeners when dissolved in a solvent compared to use of single aptamer. These aptamers are expected to provide a tool for preliminary screening or quick separation of PBDEs in environmental samples prior to trace quantitative analysis.     

Natural sunlight and sun simulator photolysis studies of tetra- to hexa-brominated diphenyl ethers in water using solid-phase microextraction

Photo-solid-phase microextraction (photo-SPME) is combined for the first time with natural and simulated sunlight to study the photochemical behaviour of environmental concerning tetra- to hexa-brominated diphenyl ethers. The sunlight photodegradation kinetics of five brominated diphenyl ethers (BDE 47, BDE 100, BDE 99, BDE 154 and BDE 153) has been studied. These BDEs are the most abundant congeners in penta-BDE commercial formulations used as flame-retardants and are considered among the most toxic ones. The five studied BDEs were photolytically labile. The detected photodegradation products include more stable lower brominated diphenyl ethers and polybrominated dibenzofurans (PBDFs). The photoformation and decay kinetics of these photoproducts were also monitorized by photo-SPME. Aqueous photodegradation studies have also been carried out. In this case, SPME is only used as the extraction technique. Obtained results in the aqueous photodegradation experiments were compared with those obtained in photo-SPME experiments.     

New multiresidue analytical method dedicated to trace level measurement of brominated flame retardants in human biological matrices

A new method has been developed for the multi-residue measurement of the main brominated flame retardants (alpha- and gamma-hexabromocyclododecane (HBCD), tetrabromobisphenol A (TBBP-A) and polybrominated diphenyl ethers including decabromodiphenyl ether) in human biological matrices (serum, adipose tissue and breast milk). The proposed sample preparation procedure focused on reduced solvent and consumable consumption and associated procedural contamination, as well as reduced sample size. This protocol was fully validated and was proved to be suitable for identification of brominated flame retardant residues at ultra-trace level, as attested by preliminary results on real samples.     

Large-volume programmed-temperature vaporiser injection for fast gas chromatography with electron capture and mass spectrometric detection of polybrominated diphenyl ethers

A large volume injection fast-GC-MS method has been developed, optimized and evaluated for the determination of polybrominated diphenyl ethers, including the decabrominated diphenyl ether (BDE-209). The programmed-temperature vaporiser injection parameters, temperature programming of the GC oven, and the physical dimensions of the narrow bore GC column were investigated to find the optimal operating conditions for the analysis. Depending on parameter settings the yield of the PBDEs and particularly BDE-209, varies significantly. Volumes up to 125 microl were successfully injected and a fast GC separation was performed, with retention times as short as 6.4 min for the last eluting compound, BDE-209. In a pilot study an air sample, collected at an electronics dismantling facility, was analyzed. Low-resolution mass spectrometry in electron capture negative ion mode was used for detection. Nine BDE congeners, including BDE-209, were identified and quantified.     

Determination of emerging and priority industrial pollutants in surface water and wastewater by liquid chromatography–negative electrospray ionization tandem mass spectrometry

A method for the simultaneous determination of six perfluoroalkyl compounds (perfluorooctanesulfonic acid (PFOS) and five perfluoroalkyl carboxylic acids), five phenolic compounds (nonylphenol (NP), bisphenol A (BPA), and methyl-, ethyl- and propylparabens), and the brominated flame retardant hexabromocyclododecane (HBCDD) in surface water and effluent wastewater has been developed. The selected pollutants include eight of the industrial pollutants (PFOS and derivatives, NP, and HBCDD) that could be regulated in surface water according to an European Union Directive proposal and four compounds of great concern because their estrogenicity (BPA and parabens). The method is based on solid-phase extraction and determination by high-performance liquid chromatography–triple quadrupole mass spectrometry in negative electrospray ionization mode. Method quantitation limits of NP, PFOS and derivatives, and HBCDD allow its application for routinely control of surface water according to the EU proposal of directive.

Milk and serum standard reference materials for monitoring organic contaminants in human samples

Four new Standard Reference Materials (SRMs) have been developed to assist in the quality assurance of chemical contaminant measurements required for human biomonitoring studies, SRM 1953 Organic Contaminants in Non-Fortified Human Milk, SRM 1954 Organic Contaminants in Fortified Human Milk, SRM 1957 Organic Contaminants in Non-Fortified Human Serum, and SRM 1958 Organic Contaminants in Fortified Human Serum. These materials were developed as part of a collaboration between the National Institute of Standards and Technology (NIST) and the Centers for Disease Control and Prevention (CDC) with both agencies contributing data used in the certification of mass fraction values for a wide range of organic contaminants including polychlorinated biphenyl (PCB) congeners, chlorinated pesticides, polybrominated diphenyl ether (PBDE) congeners, and polychlorinated dibenzo-p-dioxin (PCDD) and dibenzofuran (PCDF) congeners. The certified mass fractions of the organic contaminants in unfortified samples, SRM 1953 and SRM 1957, ranged from 12 ng/kg to 2200 ng/kg with the exception of 4,4′-DDE in SRM 1953 at 7400 ng/kg with expanded uncertainties generally <14 %. This agreement suggests that there were no significant biases existing among the multiple methods used for analysis.

鱼肉组织中多溴联苯醚的定量分析

多溴联苯醚(PBDEs)是一类广泛用于家用电器、电子产品、塑料泡沫、家居装饰材料等行业的添加型阻燃剂[1],使用量最多的是五溴联苯醚(penta-BDE),八溴联苯醚(octa-BDE)和十溴联苯醚(deca-BDE)3种[2]。最近的研究表明[4-6],多溴联苯醚已广泛地存在于各种环境介质、生物体及人体中     

Kinetics of thermal and photolytic degradation of decabromodiphenyl ether (BDE 209) in backcoated textile samples

Kinetics of the thermal and photolytic degradation of decabromodiphenyl ether (DBE 209) was studied using HPLC. Samples lost an amount of ∼8.4% (w/w), 24% (w/w), 39.4% (w/w) and 28.5% of the amount of DBE 209 originally present in the samples due to ageing at 25, 60, 90 °C and UV exposure, respectively. The thermal and photolytic release was found to follow the first order kinetics with rate constants estimated to be 3.6 × 10⁻³, 1.03 × 10⁻², 3.6 × 10⁻² and 3.94 × 10⁻² day⁻¹, respectively. Ageing of the textile samples enhanced the release of the DBE 209 from the backcoated textile. Photodegradation of BDE 209 into lower congeners of brominated flame retardants was also observed for the UV-aged samples.Migration of DBE 209 from the backcoated textile into biological fluids was studied using Head-over-Heels and contact-Blotting test for unaged, thermally and UV aged samples. The presence of biological fluids (sweat, saliva and juice) was found to enhance the migration of DBE 209 compared to water. Migration of BDE 209 into artificial biological fluids is significantly increased for samples previously exposed to UV radiation or thermally aged. An increase from 0.6% (w/w) to a maximum of 2% (w/w) of the amount of BDE 209 migrated into artificial biological fluids due to ageing conditions in the presence of biological fluid was recorded.     

HPLC isolation and NMR structure elucidation of the most prominent octabromo isomer in technical octabromo diphenyl ether

The major octabromo isomer of technical octabromo diphenyl ether mixture (technical octaBDE) DE-79 was isolated by RP-HPLC. Three serially coupled columns (each 250 mm long) enabled a good separation of the target compound from other congeners using 100% ACN as eluent. Approximately 100 microg of the target compound was isolated with a purity of >90% and investigated by MS for confirmation of the degree of bromination. 1H-NMR and 2-D 1H-13C correlation NMR spectra unequivocally clarified that the octaBDE in question is 2,2',3,3',4,4',6,6'-octabromodiphenyl ether (BDE 197). Based on annual production rates of technical BDE products (1999/2001), approximately 380 tons of BDE 197 were annually produced which, on the long term, may enter the environment. Compared with other individual BDE congeners, BDE 197 has the seventh highest application rate. Reductive debromination of BDE 197 can lead to four hepta-, 15 hexa-, 23 penta-, and 28 tetra-BDE isomers, respectively. This variety includes all known major BDEs of environmental concern (BDE 47, 85, 99, 100, 153, 154, and 183). The identification of BDE 197 in technical octaBDE DE-79 strongly suggests that research on the environmental fate of BDEs should include this key-BDE congener.     

Results of an interlaboratory comparison on the determination of polybrominated flame retardants in poly(ethyleneterephthalate)

An intercomparison to establish the performance of routine laboratories in the determination of polybrominated flame retardants in polymers was organised. Commercial poly(ethyleneterephthalate) was fortified with technical pentabromodiphenyl ether, octabromodiphenyl ether and decabromodiphenyl ether mixtures and with a decabromobiphenyl technical mixture at 0.4–0.8 g/kg. Homogeneity and stability of the total Br content in the material was confirmed. Thirty-seven laboratories from Europe, Asia and the Americas submitted results. Relative repeatability standard deviations for individual congeners ranged from 7 to 17%. Relative between-laboratory standard deviations ranged from 22 to 61%. No significant influence of a common standard, application of a standard method or method parameters could be identified. The quality and uncertainty of the results of this study are significantly worse than those reported in the environmental field and indicate a clear need for a learning process among the laboratories involved. Figure Mandel’s h (between labs): critical level: 1.91     

Analysis of polybrominated diphenyl ethers (PBDEs) by liquid chromatography with negative-ion atmospheric pressure photoionization tandem mass spectrometry (LC/NI-APPI/MS/MS): application to house dust

Eight polybrominated diphenyl ether (PBDE) congeners of primary interest to the US EPA were separated using reverse-phase liquid chromatography on an octadecylsilane column. BDE-28, BDE-47, BDE-99, BDE-100, BDE-153, BDE-154, BDE-183, and BDE-209 were baseline-resolved under isocratic conditions in 92:8 methanol/water (v/v). Negative-ion atmospheric pressure photoionization (NI-APPI) with a toluene dopant produced precursor ions corresponding to [M–Br+O]^– for the eight congeners studied. Each congener was quantified by tandem mass spectrometry through a unique multiple reaction monitoring (MRM) transition. On-column limits of detection were between 2.4 and 27.8 pg for the eight congeners studied, with an intra-day method precision of 9%. The LC/NI-APPI/MS/MS method was validated for the analysis of the eight PBDE congeners in NIST SRM 2585 (Organics in House Dust). Pressurized liquid extraction (PLE) with subsequent LC/NI-APPI/MS/MS analysis afforded quantitative recovery for all eight PBDE congeners with recoveries ranging from 92.7 to 113%. The liquid-phase separation of the LC/NI-APPI/MS/MS method is not prone to the thermal degradation issues that plague splitless GC based analyses of highly brominated PBDEs such as BDE-209.     

Microwave-assisted extraction (MAE) for the determination of polybrominated diphenylethers (PBDEs) in sewage sludge

An efficient microwave-assisted extraction (MAE) method has been developed and evaluated for the quantification of eight major polybrominated diphenylethers (PBDEs) in sewage sludge. The PBDEs were extracted from wet and dry sludge in a microwave extraction unit using a hexane/acetone mixture for 35 min at a controlled temperature of 130 °C. The extract was concentrated, cleaned up on a silica gel column, and analyzed by gas chromatography/mass spectrometry (GC/MS) in the negative chemical ionization (NCI) mode. The MAE procedure exhibited higher extraction efficiency, specifically for BDE (brominated diphenylether) 209, than the conventional Soxhlet extraction. The test congeners were clearly separated under specific instrumental operating conditions, at a source temperature of 230 °C and a column length of 20 m. The present analytical method showed recovery efficiencies ranging from 80 to 110% when applied to the PBDE-free sludge spiked with eight PBDE congeners. The efficiency of the MAE method was confirmed using sludge obtained from four sewage treatment plants (STPs). The results indicate that BDE 47, 99, and 209 are the most abundant congeners present in these sewage sludges, which is consistent with previous reports.     

超声辅助碱解萃取-气相色谱-电子捕获检测器测定海洋沉积物中8种多溴联苯醚

将超声辅助碱液分解杂质与溶剂萃取相结合,采用气相色谱-电子捕获检测(GC-ECD)建立了一种快速高效净化、萃取海洋沉积物中8种常见多溴联苯醚(PBDEs)的分析方法。样品在2.00 mol/L NaOH甲醇溶液中超声30 min,经正己烷萃取、单层硅胶净化、正己烷洗脱、旋蒸浓缩后定容至100 μL,采用GC-ECD分析。结果表明,PBDEs各单体的加标回收率为63.6%~110.3%,相对标准偏差(RSD)为1.7%~15.5%(n=5);十溴联苯醚(BDE-209)的检出限为0.097 ng/g,其他7种单体的检出限为0.002~0.011 ng/g(信噪比为3)。该方法的准确度和精密度较高,稳定性和回收率良好,可满足沉积物中PBDEs的分析要求。利用建立的方法测定了渤海表层沉积物中PBDEs的含量,8种PBDEs总含量在1.566~6.760 ng/g之间,其中BDE-209的含量为1.461~6.438 ng/g,总体呈现出由近岸向远岸递减的趋势,表明人为活动、表层冲刷和陆地河流的输入对渤海地区PBDEs的含量有重要影响。