Accurate determination of hexabromocyclododecane diastereomers in extruded high-impact polystyrene: Development of an analytical method as a candidate reference method

Determination of Hexabromocyclododecane in Expanded Polystyrene and Extruded Polystyrene Foam by Gas Chromatography-Mass Spectrometry

A gas chromatography-mass spectrometry (GC/MS) method for the determination of hexabromocyclododecane (HBCD) in expanded polystyrene and extruded polystyrene foam (EPS/XPS) was developed. The EPS/XPS samples were ultrasonically extracted with acetone and the extracts were purified by filtration through a microporous membrane (0.22 μm) and solid-phase extraction. The samples were analyzed using a GC/MS using the selected ion monitoring mode. The ions 157, 319 and 401 were selected as the qualitative ions, while ion 239 was chosen as the quantitative ion. An HBCD standard working solution with a concentration range of 1.0–50.0 mg/L showed good linearity. The detection limit of HBCD was 0.5 mg/kg, meeting the LPC limit (<100 or 1000 mg/kg). Six laboratories were selected to verify the accuracy of the method, and 10 samples were tested. The interlaboratory relative standard deviation range was 3.68–9.80%. This method could play an important role in controlling HBCD contamination in EPS/XPS.

Spatial distribution, source identification, and anthropogenic effects of brominated flame retardants in nationwide soil collected from South Korea

Soil samples were collected at 61 sites of the national monitoring network for persistent organic pollutants (POPs) in South Korea. The target compounds were brominated flame retardants (BFRs), including polybrominated diphenyl ethers (PBDEs), polybrominated biphenyls (PBBs), hexabromocyclododecanes (HBCDDs), and tetrabromobisphenol A (TBBPA). The mean concentrations of Σ₂₇ PBDEs, Σ₃ HBCDDs, and TBBPA in soil were 222, 17.2, and 4.4 ng/g, respectively, but PBBs were not detected. Industrial sites had statistically higher BFR concentrations than suburban sites but no significant difference compared with urban sites. The commercial deca-BDE mixtures were the most likely source of PBDE contamination in the soil samples, with the minor influence of commercial penta-BDE and octa-BDE mixtures. The profiles of HBCDDs in most soil samples differed from those in the powder types of technical HBCDD mixtures, indicating that they are affected by the HBCDDs contained in commercial products and the conversion of HBCDD diastereoisomers (γ-HBCDD to α-HBCDD) in the environment. The concentrations of Σ₂₇ PBDEs, Σ₃ HBCDDs, and TBBPA were significantly correlated with population density, gross domestic product, and the number of companies (p < 0.01), indicating a direct impact of anthropogenic activities. Significant correlations among BFRs were determined (0.63 < r < 0.74, p < 0.01), suggesting that these pollutants had similar sources. Relatively good correlations (0.44 < r < 0.98, p < 0.01) between BDE-209 and other light BDEs (except for BDE-71, -77, -126, -156, and -205) might result from the degradation of heavy BDEs under anaerobic and natural sunlight conditions. To the best of our knowledge, this study provides the most comprehensive soil monitoring data for various BFRs in South Korea. Furthermore, it is the first report on soil contamination by deca-BDE, HBCDDs, and TBBPA in South Korea.

Transfer of POP-BFRs within e-waste plastics in recycling streams in China

Due to the rapid increase of e-waste plastics and the national policy's strong preference for mechanical recycling, a substantial amount of POP-BFRs is flowing into recycling streams in China. Therefore, confronting with the worldwide prohibition in manufacturing and consumption, identifying the transfer and inventory of POP-BFRs in recycling stage has become the key to their effective management and elimination. In this study, the level of PBDEs in e-waste housings, recycled plastics and daily-use products from recycling facilities and the commodity market was determined, and a gradual decrease of PBDEs was observed along with the downstream life cycle, indicating that recycling is a crucial medium of POP-BFRs transferred from their original use to an expansive reutilization market. Based on that, an extrusion experiment was conducted to imitate the mechanical recycling of e-waste plastics. It was found that, about 77% of PBDEs and 39% of HBCD were retained in recycled materials, with levels comparable to those in the products from recycling manufacturers and the consumer market. Mechanical recycling had no effect on the predominance of highly brominated BDE congeners, and no obvious transformation from higher to lower brominated diphenyl ethers was observed in recycled materials under thermal conditions; however, the isomerization of γ-HBCD brought about a noticeable increase in the relative abundance of α-HBCD. According to a Monte Carlo method estimation by using the transfer rate, approximately 235-687.8 tons of PBDEs have entered into recycling streams annually in the most recent five years. The field survey, laboratory findings and model evaluation results obtained in this study would not only contribute to a broader understanding of POP-BFRs sources and impact scopes posed on human health and the environment, but also provide a basis for developing effective strategies to manage POP-BFRs from the recycling perspective.

Distribution and diastereoisomeric profiles of hexabromocyclododecanes in air, water, soil, and sediment samples in South Korea: Application of an optimized analytical method

In this study, the levels and distribution patterns of HBCD diastereoisomers in air, water, soil, and sediment samples in South Korea were investigated after optimizing the UPLC-MS/MS analytical process. Extraction and cleanup efficiencies were tested using several different extraction solvents and adsorbents. Dichloromethane was selected as the base extraction solvent, and multi-layer silica gel (MSG) and MSG-alumina columns were selected for the removal of HBCDs from complex environmental matrices. The concentration of Ʃ₃ HBCDs was 22-133 pg/m³, 10-128 ng/g, 0.2-151 ng/L, and 0.5-552 ng/g dw for air, soil, water, and sediment samples, respectively. Relatively higher concentrations of Ʃ₃ HBCDs were observed at stations adjacent to industrial facilities (e.g., rubber and plastic, textile, chemical, fabricated metal, and wholesale trade factories) associated with the use of commercial HBCDs. The proportion of γ-HBCD in the soil (48.3-86.2%) and sediment (54.2-78.1%, except for one station) samples was similar to that found in technical and commercial HBCDs. In contrast, α-HBCD (52.3-71.2%) was dominant in all air samples, while the water samples displayed no clear trend in their diastereoisomer profiles. As the first nationwide report on HBCD diastereoisomers in the environment, this study demonstrates that most environmental compartments in South Korea are moderately contaminated with HBCDs.

Occurrence, levels and profiles of brominated flame retardants in daily-use consumer products on the Chinese market

With the global phasing-out of POP-BFRs (brominated flame retardants restricted under the Stockholm Convention on Persistent Organic Pollutants), the main challenge for their environmentally sound management has shifted from manufacturing and consumption to their recycling and disposal. For the end-of-life products containing POP-BFRs, material recycling and reuse in new articles is the favorite approach widely adopted by recyclers. This would result in POP-BFRs being transferred into daily-use consumer products. To identify the possible reservoirs of POP-BFRs in consumer products on the Chinese market, 120 samples were screened for Br by using a portable X-ray fluorescence (XRF) spectrometer, and the three traditional BFRs, i.e., polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCD) and tetrabromobisphenol A (TBBPA), were analyzed in 15 Br-positive samples. The results showed that 36.7% of products contained at least one test point positive for Br, and higher detection frequencies were found in electric appliances and toys. The concentrations of ∑BFRs ranged from 0.48 to 73.82 mg kg-1 with a general contribution in the order of ∑PBDEs > TBBPA > HBCD. BDE-209 was the dominant congener among PBDEs in most investigated samples, accounting for 48.18-99.36%. Relatively high proportions of the more bioaccumulative and toxic substances of lower brominated PBDE congeners and α-HBCD in products may increase the adverse impacts on the environment and human health. The obtained results will be helpful to understand the downstream flow of POP-BFRs with great significance to the control on their unintended contamination in daily life.