Determining Polybrominated Diphenyl Ethers in Surface Waters of Western Pomerania Using Gas Chromatography with Electron Capture Detection

Pol. J. Environ. Stud. Vol. 24, No. 3 (2015), 961-968 DOI: 10.15244/pjoes/34010 Original Research Determining Polybrominated Diphenyl Ethers in Surface Waters of Western Pomerania Using Gas Chromatography with Electron Capture Detection Marlena Byczkiewicz*, Maciej Jabłoński** Institute of Chemistry and Environmental Protection, West Pomeranian University of Technology, Al. Piastow 42, 71-065 Szczecin, Poland Received: 10 October 2014 Accepted: 29 December 2014 Abstract We show how to determine polybrominated diphenyl ethers in aqueous samples using liquid-liquid extraction and gas chromatography with electron capture detection (LLE-GC-μECD). This method, due to its simplicity, low limits of determination (7-9 pg/L), high accuracy, relatively low costs, and high recovery coef- ficients for all of these PBDEs (86-92%), offers enormous benefits for routine analyses of PBDEs. The developed method was applied to surface water samples collected from different sampling points in western Pomerania. Keywords: polybrominated diphenyl ethers, surface water, gas chromatography, liquid-liquid extraction Introduction the transfer and dissemination of PBDEs in the environment. Particularly toxic are the following PBDEs: BDE-28, Polybrominated diphenyl ethers (PBDEs) are classified BDE-47, BDE-99, BDE-100, BDE-153, and BDE-154. as persistent organic pollutants. They are added to plastics, Most of these congeners are part of a commercial prepara- paints, coatings, and textiles, as well as resins and poly- tion to delay the combustion process – pentaBDE [3]. meric materials to reduce their flammability without the PBDE solubility in water decreases with increases in formation of chemical bonds between the additives and the the number of bromine atoms in the molecule, and the polymeric materials [1-4]. PBDEs are a major danger in the partition coefficient octanol/water expressed as log Kow environment because of their constancy, potential ease of increases with the number of bromine atoms in the mole- getting into it, and toxicity [1-3]. Studies have confirmed cules of these compounds [4]. Substances with a minor their presence in aquatic and terrestrial elements of the amount of bromine in the molecule, such as BDE-47 and environment, for example air, water, sediments, fish, clams, BDE-99, are 90% of the total content determined in the birds, mammals, and human tissues [1, 5-8]. aqueous phase. Congeners with higher content of bromine Water as a universal solvent and important agent of trans- are more strongly bound to the sediment particles, making portation of micropollutants can significantly contribute to them less mobile in the environment. Literature data on the occurrence of PBDEs in water is limited due to the *e-mail: [email protected] fact that these compounds are practically insoluble in **e-mail: [email protected] water [3, 4]. 962 Byczkiewicz M., Jabłoński M. In November 2011, a Regulation of the Minister of the The solvent used for extracting n-hexane SupraSolv was Environment introduced monitoring of polybrominated produced by Merck (Darmstadt, Germany). For drying the diphenyl ethers in surface waters. According to require- extracts we applied sulfate (VI) of sodium produced by ments of minister for environmental regulation, the analyt- Avantor (Gliwice, Poland). ical method for marking PBDEs in superficial water should: get the exact result at the same time as achieve a Apparatus very low limit of determination (60 pg/l) and measurement doubt (k=2), which is less than 50%. It should also be easy To determine the concentrations of PBDEs we used an in preparation and not require large financial input. Due to Agilent Technologies 6890N gas chromatograph with analytical problems, only the Provincial Inspectorate for micro–electron capture detector (μECD). The analytes were Environmental Protection in Szczecin (WIOŚ) performed separated in a ZB-XLB capillary column (30 m×0.32 mm such studies (in 2012). In 2013 results of polybrominated I.D., 0.25 μm film thickness, Phenomenex) using a constant diphenyl ethers in superficial water realized WIOŚ in helium flow of 2.6 mL/min. The GC oven temperature was Szczecin and also WIOŚ in Gdansk. programmed from 120ºC (1.17 min) to 320ºC at 5ºC/min. This paper aims to elaborate on the method of deter- The injector and detector temperatures were set at 250ºC mining PBDEs in surface waters, which will be character- and 320ºC, respectively. The injection was performed in the ized by high accuracy and precision of the results and ade- pulsed splitless mode. The nitrogen (makeup gas) flow in quately low detection limits for individual congeners the micro-ECD system was fixed at 45 mL/min. (<10 pg/L). This method should be particularly useful for routine analysis and would also allow for the characteriza- Experimental tion of PBDEs in similar aqueous matrices at relatively low cost, and be an easy way for sample preparation. The elab- In the presented method, the sample having of 100 mL orated methodology for determining PBDE measurements was placed in amber glass bottles and 2.5 mL of n-hexane was used for measuring the concentrations of these com- was added. Next, the sample was stirred using a magnetic pounds in water samples collected at different sampling stirrer to facilitate complete mixing of the solvent with the points in western Pomerania. water (about 1000 rpm/min) for 30 minutes. The samples were then separated in a separator funnel and the organic Materials and Methods phase, which was further dried over anhydrous sodium sulfate, was transferred into conical flasks. The resulting Standards and Reagents extract was concentrated to 100 µL. Then the concentrated sample was analyzed by gas chromatography. During the Individual unlabelled PBDE standards, namely BDE- method development an assessment of the influence of 28, BDE-47, BDE-99, BDE-100, BDE-153, and BDE- extractant volume and mixing time on analyte recovery was 154, were supplied by Cambridge Isotope Laboratories, performed. For this purpose two extractant volumes, name- Inc. USA. This standard included in its composition the ly 2.5 and 5.0 mL, were employed at different mixing times following congeners, each at a concentration of 1 ng/μL. of 15, 30, and 60 minutes. Fig. 1. Control – measurement locations in 2012. Determining Polybrominated Diphenyl Ethers... 963 Fig. 2. Control – measurement locations in 2013. Six calibration solutions ranging from 0.05 to 0.5 µg/L obtained for the samples of surface water. Fig. 4 shows the were prepared by serial dilution. chromatogram of the PBDE sample. The graph in Fig. 5 Samples of distilled water were enriched with a known shows the influence of the volume of the extraction solvent amount of the target analytes in a solvent miscible with and the mixing time for recovery. It was found that only water (acetone) and were subjected to extraction, purifica- volume equal to 2.5 mL of the extractant and the mixing tion, concentration and chromatographic analysis. time 30 min. and the volume of 5.0 mL and 60 minutes To investigate the analytical recoveries of individual mixing time gave satisfactory recoveries for all congeners. PBDE congeners, a pure water matrix was divided into two On this basis, subsequent extraction was based on a volume parts, and then enriched by known volume of PBDE stan- of 2.5 mL of the extractant and mixing time equal to 30 dard solution in a solvent miscible with water (acetone) and minutes. was subjected to extraction, purification, concentration, and Competence in the determination of PBDEs has been chromatographic analysis. confirmed in proficiency testing AQUACHECK PT Round Research should approve analysis in water samples of 457 organized by LGC Standards Proficiency Testing. For PBDE with a liquid-liquid extraction and gas chromatogra- individual PBDEs we achieved satisfactory results (z score phy with electron capture detection. Experiments were <1). allowed to define the parameters that describe the method The literature contains many studies on the determina- used: linear range of calibration, accuracy, precision, limit tion of PBDEs using a wide variety of sample preparation of detection, limit of quantification, and the degree for sep- techniques. Table 3 shows the number of the most popular arate analyses from aqueous matrix. In western Pomerania and compared with the proposed method based on the samples were taken for testing PBDE in 15 measuring extraction of the liquid phase. Under the considerations we checkpoints, one year after only in 11 (see locations in Figs. took the level of recovery of the analytes from the matrix, 1 and 2). Collection samples of river water were realized the size of the sample, and sample processing time for prop- 12 times during a year (once a month). Samples were collected into dark glass bottles and stored at 4ºC. O Results and Discussion Bry Polybrominated diphenyl ethers are formed by the direct bromination of organic molecules or by the addition of bromine to alkenes [1]. Fig. 3 shows the structure of PBDE molecules and Table 1 presents select information about these compounds. Table 2 summarizes the validation parameters obtained Brx from the newly developed method. The results were Fig. 3. Chemical structure of PBDEs, where x + y = 1-10. 964 Byczkiewicz M., Jabłoński M. Table 1. Select information about PBDE. Chemical name Acronym CAS No. Formula log Kow [9] 2,4,4’-tribromodiphenyl ether BDE-28 41318-75-6 C12H7Br3O 6.0±0.6 2,4,2’,4’-tetrabromodiphenyl ether BDE-47 5436-43-1 C12H6Br4O 7.4±0.7 2,4,2’,4’,5- pentabromodiphenyl ether BDE-99 60348-60-9 C12H5Br5O 8.2±0.8 2,4,2’,4’,6- pentabromodiphenyl ether BDE-100 189084-64-8 C12H5Br5O 8.0±0.8 2,4,2’,4’,5,5’- hexabromodiphenyl ether BDE-153 68631-49-2 C12H4Br6O 8.9±0.7 2,4,2’,4’,5,6’-hexabromodiphenyl ether BDE-154 207122-15-4 C12H4Br6O 9.0±0.7 Table 2.

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