Determination of polybrominated diphenyl ethers in ... - Springer Link

Anal Bioanal Chem (2007) 387:2365–2379 DOI 10.1007/s00216-006-1054-5

ORIGINAL PAPER

Determination of polybrominated diphenyl ethers in environmental standard reference materials Heather M. Stapleton & Jennifer M. Keller & Michele M. Schantz & John R. Kucklick & Stefan D. Leigh & Stephen A. Wise

Received: 12 October 2006 / Revised: 27 November 2006 / Accepted: 28 November 2006 / Published online: 6 January 2007 # Springer-Verlag 2007

Abstract Standard reference materials (SRMs) are valuable tools in developing and validating analytical methods to improve quality assurance standards. The National Institute of Standards and Technology (NIST) has a long history of providing environmental SRMs with certified concentrations of organic and inorganic contaminants. Here we report on new certified and reference concentrations for 27 polybrominated diphenyl ether (PBDE) congeners in seven different SRMs: cod-liver oil, whale blubber, fish tissue (two materials), mussel tissue and sediment (two materials). PBDEs were measured in these SRMs, with the lowest concentrations measured in mussel tissue (SRM 1974b) and the highest in sediment collected from the New York/New Jersey Waterway (SRM 1944). Comparing the relative PBDE congener concentrations within the samples, we found the biota SRMs contained primarily tetrabrominated and pentabrominated diphenyl ethers, whereas the sediment SRMs contained primarily decabromodiphenyl H. M. Stapleton : M. M. Schantz : S. A. Wise Analytical Chemistry Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA J. M. Keller : J. R. Kucklick Analytical Chemistry Division, Hollings Marine Laboratory, National Institute of Standards and Technology, Charleston, SC 29412, USA S. D. Leigh Statistical Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA Present address: H. M. Stapleton (*) Duke University, Nicholas School of the Environment and Earth Sciences, Durham, NC 27708, USA e-mail: [email protected]

ether (BDE 209). The cod-liver oil (SRM 1588b) and whale blubber (SRM 1945) materials were also found to contain measurable concentrations of two methoxylated PBDEs (MeO-BDEs). Certified and reference concentrations are reported for 12 PBDE congeners measured in the biota SRMs and reference values are available for two MeOBDEs. Results from a sediment interlaboratory comparison PBDE exercise are available for the two sediment SRMs (1941b and 1944). Keywords Polybrominated diphenyl ethers . Standard reference materials . Certified reference materials . Fish tissue . Sediment . Methoxylated polybrominated diphenyl ethers

Introduction Polybrominated diphenyl ethers (PBDEs) are a class of brominated flame retardants that are now considered ubiquitous and persistent contaminants. In 2003, the world market demand for the three commercial mixtures of PBDEs was over 60,000 t [1]. The commercial mixtures, commonly referred to as pentaBDE, octaBDE and decaBDE, all possess PBDE congeners with varying degrees of bromine substitution. These compounds are added to numerous plastics and resins to decrease their flammability. Owing to their widespread applicability, PBDEs are found in a variety of products, including television sets, cell phones, furniture, carpets and a variety of common electronic and building materials [2–4]. Over the past decade, reports have documented an increasing abundance of PBDEs in environmental matrices, including bird eggs, fish, marine mammals and sediments [5–8] and numerous reviews have been written on their environmental prevalence [9–11]. Of particular

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concern is the increasing abundance of PBDEs measured in human fluids and tissues such as serum, milk and adipose tissue [12–15]. Current studies suggest that both diet and indoor environments (i.e., air and house dust) are likely routes of exposure for adults and children to PBDEs [16– 20]. Owing to increasing concern over the persistence, bioaccumulation and potential toxicity of these chemicals, both the pentaBDE and octaBDE commercial formulations have been voluntarily taken off the market in the USA and banned from use in the European Union [21, 22]. However, decaBDE use continues without restriction and recent studies suggest terrestrial food webs may be more prone to decaBDE bioaccumulation than aquatic food webs [23, 24]. With the increased attention on PBDEs, numerous laboratories have been investigating and measuring PBDEs in environmental and human samples. To perform these measurements with the greatest accuracy, it is beneficial to have reference materials with known concentrations of analytes of interest to validate results. For over two decades, the National Institute of Standards and Technology (NIST) has provided natural matrix certified reference materials (CRMs) with homogenous compositions and properties to aid in analytical method development and validation of measurements of organic and inorganic compounds. These standard reference materials (SRMs) include matrices such as sediment, fish tissue, fish oil, whale blubber, mussel tissue and human serum, and food products such as peanut butter, baking chocolate and infant formula. The environmental SRMs have previously been measured for persistent organochlorine pesticides such as dichlorodiphenyltrichlorethane (DDT), polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) [25–29]. Here we report additional measurements for selected PBDE congeners detected in these environmental SRMs.

Materials and methods Materials The environmental SRMs surveyed were prepared by the NIST in Gaithersburg, MD and have been previously certified for concentrations of persistent organic contaminants including PAHs, PCBs and organochlorine pesticides [25–29]. More information on the preparation of each individual SRM can be found in the certificates of analysis available from the NIST SRM catalog Web site at http://www.nist.gov/srm/. PBDEs were measured in the following SRMs: SRM 1588b Organics in Cod Liver Oil, SRM 1941b Organics in Marine Sediment, SRM 1944 NewYork/New Jersey Waterway Sediment, SRM 1945 Organics in Whale Blubber,

Anal Bioanal Chem (2007) 387:2365–2379

SRM 1946 Lake Superior Fish Tissue, SRM 1947 Lake Michigan Fish Tissue, SRM 1974b Organics in Mussel Tissue (Mytilus edulis), SRM 2977 Mussel Tissue (Organic Contaminants and Trace Elements) and SRM 2978 Mussel Tissue (Organic Contaminants-Raritan Bay, NJ). SRMs were extracted and analyzed for PBDEs at NIST laboratories located in Gaithersburg, MD and Charleston, SC. Additional PBDE measurements made by Zhu and Hites [30] were included in the assignment of certified and reference values for PBDE congeners in selected SRMs. The PBDE calibration solutions used by NIST were prepared from 27 individual neat congeners purchased from Accustandard (New Haven, CT, USA). Two methoxylated PBDE standards (2′-methoxy-2,3′,4,5′-tetrabromodiphenyl ether, 2′-MeO-BDE 68, and 6-methoxy-2,2′,4,4′-tetrabromodiphenyl ether, 6-MeO-BDE 47) were purchased from Cambridge Isotope Laboratories (Andover, MA, USA). Internal standards were purchased from Cambridge Isotope Laboratories (Andover) and Wellington Laboratories (Guelph, ON, Canada) and included five isotopically labeled (13C) compounds: 4,4-dibromodiphenyl ether (BDE 15L); 2, 2′,3,4,5-pentachlorodiphenyl ether (CDE 86L); 2,2′,4,4′,5-pentabromodiphenyl ether (BDE 99L); 2,3′,4,4′,5-pentachlorobiphenyl (PCB 118L), and 2,2′,3,3′,4,4′,5,5′,6,6′-decabromodiphenyl ether (BDE 209L). Throughout this paper, the PBDE congeners are numbered according to IUPAC rules. All solvents used were high-performance liquid chromatography (HPLC) grade or better. Sample extraction and quantification Three to six replicates of each SRM were extracted and analyzed for selected PBDEs by the NIST laboratories using three different methods. Figure 1 provides a brief description of the methods used for the analysis of the SRMs among the different laboratories. These methods were similar to methods used in Stapleton et al. [31]. The two sediment SRMs, 1941b (Organics in Marine Sediment) and 1944 (NewYork/New Jersey Waterway Sediment), were analyzed for PBDEs during an interlaboratory comparison exercise [31]. Twelve laboratories from six different countries participated in this exercise, and results are presented here. At the NIST laboratory in Gaithersburg, two sets of each SRM were extracted by pressurized fluid extraction (PFE), and the extracts were cleaned using solid phase extraction (SPE) cartridges. These extracts were analyzed using two different gas chromatography/mass spectrometry (GC/MS) ionization methods: electron impact ionization (GC/EI-MS; method 1) and electron capture negative chemical ionization (GC/ECNI-MS; method 2). The NIST Charleston laboratory used a slightly different method of extraction

Anal Bioanal Chem (2007) 387:2365–2379

Method 1 NIST Gaithersburg

Method 2 NIST Gaithersburg

Pressurized Fluid Extraction 6 replicates CH2Cl2


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Method 3 NIST Charleston

Method 4 Indiana Universitya


Soxhlet Extraction 4 to 6 replicates 50:50 Acetone:Hexane

GPC and Alumina Clean-up GPC and Silica Clean-up

GC/EI-MS Splitless injection 15 m DB-5MS

Sulfuric Acid, Silica and Alumina Clean-up

GPC and Silica Clean-up

GC/ECNI-MS GC/ECNI-MS GC/EI-MS On-column injection On-column injection On-column injection 15 m DB-5MS 15 m DB-5MS 60 m DB-5MS 4 congeners 24 congeners

GC/ECNI-MS Splitless injection 60 m DB-5MS

Fig. 1 Methods used for the determination and quantification of PBDEs in the SRMs a See Zhu and Hites, 2003 [30] for details

and cleanup (described below) on a third set of each SRM. These extracts were analyzed using GC/EI-MS for most congeners and were injected again using GC/ECNI-MS for the higher-brominated congeners (method 3). These method numbers are referred to throughout the paper and are referenced in Tables 1, 2, 3, 4, 5, 6 and 7. Methods 1 and 2 employed PFE using dichloromethane (DCM). Approximately 1–3 g of wet (biota) or dry (sediment) mass was mixed with sodium sulfate and poured into a 22-mL stainless steel extraction cell. The remaining volume of each cell was filled with precleaned sodium sulfate. The contents of the extraction cells were spiked with the appropriate internal standards. Extraction cells were heated to 100 °C for 5 min and extracted with DCM at 13.8 MPa (2,000 psi). The flush volume was 60% over three static cycles. Extracts were reduced in volume using ultra-high-purity nitrogen in an automatic evaporation system. Extracts of biota SRMs were reduced to 2 mL in DCM, whereas extracts of sediment SRMs were reduced in volume and solvent exchanged into 1 mL of hexane. Biota extracts (SRMs 1588b, 1945, 1946, 1947 and 1974b) were reduced in volume and lipids were removed by size exclusion chromatography (SEC). The extracts were

injected into a HPLC system equipped with a divinylbenzene–polystyrene column (10-μm particle size, 100-Å pore size, 2.5-cm inner diameter×60 cm, PL-Gel, Polymer Labs, Amherst, MA, USA). Samples were eluted using a mobile phase of 100% DCM at a flow rate of 10 mL/min. The collected eluant (180–250 mL after injection) was concentrated in volume and transferred into hexane. Samples were further cleaned using silica SPE cartridges (Waters Co., Milford, MA, USA). Cartridges were precleaned with 10 mL of hexane. Samples were added to the cartridges, eluted with 20 mL of hexane and reduced in volume using an automated evaporation system (TurboVap II) to 0.5 mL. Method 3 employed PFE identical to methods 1 and 2 except that approximately 1–7 g of sample mass was mixed with sodium sulfate and loaded into 33-mL stainless steel extraction cells. The contents of the extraction cells were gravimetrically spiked with 0.6 mL of internal standard solution containing approximately 200 ng of BDE 99L, 200 ng of PCB 118L and 100 ng of BDE 209L. Extracts of biota SRMs, concentrated to 1 mL, were cleaned using the SEC method described above, solvent-exchanged to isooctane, evaporated to 0.5 mL, and further cleaned using 5% deactivated alumina columns on a RapidTrace (Caliper,

2368 Table 1 Concentrations of polybrominated diphenyl ethers (PBDEs) (ng/g wet mass) measured in SRM 1588b (Organics in Cod Liver Oil) using three different methods. Values represent the mean and one standard deviation

GC/EI-MS gas chromatography/electron impact ionization mass spectrometry, GC/ECNIMS gas chromatography/electron capture negative chemical ionization mass spectrometry, NM not measured. a BDEs 203, 205, 206, and 209 were measured using GC/ ECNI-MS in Method 3

Anal Bioanal Chem (2007) 387:2365–2379 Congener

BDE BDE BDE BDE BDE BDE BDE BDE BDE BDE BDE BDE BDE BDE BDE BDE BDE BDE BDE BDE BDE BDE BDE BDE BDE BDE

17 25 28/BDE 33 30 47 49 66 71 75 85 99 100 116 119 138 153 154 155 181 183 190 191 203 205 206 209

Method 1 GC/EI-MS (n=6)

Method 2 GC/ECNI-MS (n=6)

Method 3 GC/EI-MSa (n=6)