Photochemical studies of a polybrominated diphenyl ethers (PBDES) technical mixture by solid phase microextraction (SPME) (original) (raw)
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Photochemical Degradation of Polybrominated Diphenylether BDE209 Under Ultraviolet Irradiation
Springer Proceedings in Physics, 2014
Knowledge of reaction mechanism and kinetics of persistent organic pollutants are crucial to development a removal technology. Feasibility of photochemical microreactor utilization as a tool for experimental investigation of photochemical degradation of polybrominated diphenyl ethers (PBDE) was studied. The degradation of deca-BDE in the photochemical microreactor with a thin irradiated liquid layer of variable thickness was investigated. The experimental results proved the significantly higher degradation rates of PBDE when compared to the published results obtained with the conventional photochemical reactors. After several minutes in microreactor the final and major degradation products were the mono brominated congeners. The extremely fast degradation of higher-brominated congeners allowed for the complete degradation of deca-BDE down to mono-BDE within short experimental times. The results confirmed the suitability of photochemical microreactors as beneficial tool for better understanding the degradation mechanism and kinetics of photodegradation of persistent organic pollutants due to significantly shorter experimental times needed for obtaining the necessary data.
Environmental Science & Technology, 2009
The potential photochemical formation of polybrominated and mixed halogenated dibenzo-p-dioxins (PBDDs and PXDDs) from hydroxylated polybrominated and polybrominated/ chlorinated diphenyl ethers (OH-PBDEs and OH-PBCDEs) in aqueous solution was studied. The ortho-hydroxylated BDE47 derivative 6-OH-BDE47, and chlorinated derivatives 3-Cl-6-OH-BDE47, 5-Cl-6-OH-BDE47, and 3,5-Cl-6-OH-BDE47 were photolyzed under sunlight at 45 degrees N latitude in buffered waters, Mississippi River water, Lake Josephine water, and ultrapure water adjusted to the pH of the natural waters. Chemical actinometry was used to determine reactant quantum yields which were calculated to be between 0.03 and 0.21, with lower yields for the chlorinated derivatives under all conditions. Quantum yields under natural water conditions were not significantly enhanced indicating that direct photolysis is the primary process of photochemical degradation. The formation of halogenated dioxins from the outdoor photolysis of the four OH-PBDEs/OH-PBCDEs under all conditions was confirmed. Dioxin yields of 0.7-3.6% were found, with higher yields for 6-OH-BDE47 under all conditions. This study suggests that photolysis of OH-PBDEs and OH-PBCDEs is a potential formation pathway of PBDDs and PXDDs in the environment.
Rapid Communications in Mass Spectrometry, 2006
Atmospheric pressure photoionization (APPI) was assessed for the mass spectrometric analysis of polybromodiphenyl ethers (PBDEs) on the basis of a set of 17 standard compounds. Positive and negative ionization modes were both investigated. M R. ions were formed under positive ion conditions whereas the negative ion mode yielded [M-BrþO] À ions. The behavior of these APPIproduced ions towards collisional activation was studied using an ion trap mass spectrometer. In positive ion mode, the loss of Br 2 was one of the major fragmentation pathways, and was favored for ortho-substituted PBDEs. Conversely, the loss of COBr. occurred only for non-ortho-substituted congeners. The collisional excitation of [M-BrþO] À ions in the ion trap also led to the loss of Br 2 , to the elimination of HBr, and to the formation of product ions by cleavage of the ether bond. The formation of para-quinone radical anions was observed for PBDEs ranging from penta-to heptacongeners, whereas brominated aromatic carbanions were formed preferentially for the most brominated PBDEs studied in this work (hepta-or deca-BDEs). M þ. ions did not undergo this fragmentation process.
Methods for determination of polybrominated diphenyl ethers in environmental samples - review
Journal of Separation Science, 2012
Polybrominated diphenyl ethers (PBDEs) are a group of persistent organic pollutants. They are used as flame retardants in plastics, paints, varnishes and textile materials. PBDEs pose great risk to the environment because of their high persistence and ability to get into the environment easily due to the lack of chemical bonds with the matrix of materials, to which they are added. Global research studies confirmed the occurrence of those compounds in the majority of elements of water and land environment. Analysis of PBDEs in environmental samples is one of the specific analytical methods of criteria that comprise low detection limits and high selectivity. The analysis of PBDEs in environmental samples is one of the specific analytical methods, in which the main criteria are low detection limits and high selectivity. In this article, a literature review of methods for environmental sample preparation and analysis of the PBDE content was presented. The article discusses the potential of modern extraction techniques such as: solid-phase microextraction, single-drop microextraction, dispersive liquid-liquid microextraction, microwave-assisted extraction, cloud point extraction, hollow fibre-liquid phase microextraction and others for the separation of PBDEs from environmental samples with a complex matrix. Among the methods for qualitative and quantitative determination of PBDEs, a particular focus was put on gas chromatography/mass spectrometry with various injection techniques and different types of sample ionisation.
Photolysis of polychlorinated biphenyls by solid-phase microextraction
Journal of Chromatography A, 2002
The photodegradation kinetics of polychlorinated biphenyls ''on-fibre'' is described. The utilisation of solid-phase microextraction (SPME) fibres to monitor photolysis pathways and determine photoproducts constitutes a new approach that exploits the solvent-free aspect and concentration possibilities of this technique. Direct photolysis of aqueous solutions containing polychlorinated biphenyls (PCBs) was also undertaken and SPME was used in this case for photoproduct extraction purposes. Reductive dechlorination was the main decomposition mechanism in both procedures. Less-chlorinated biphenyls are the principal photoproducts and, among these, some toxic coplanar species have been detected. The influence of irradiation time was evaluated for both treatments. SPME was found to be a good choice for the extraction of photoproducts in experiments conducted in the classical way (extraction after photolysis). Moreover, it is demonstrated that photolysis of PCBs ''on fibre'' is realistic and provides the possibility of evaluating the phototransformation of these pollutants at environmental levels.
Synthesis and Characterization of 32 Polybrominated Diphenyl Ethers
Environmental Science & Technology, 1999
Polybrominated diphenyl ethers (PBDEs) are widely used as additive flame retardants in, for example, textiles, computers, television sets, and other electrical appliances. PBDEs are ubiquitous environmental contaminants, present also in humans. The environmental levels of the PBDEs are, however, still in general lower than those of polychlorinated biphenyls (PCBs). However, while the levels of PCBs generally are decreasing, those of the PBDEs are increasing in, for example, human milk. In the present study 32 individual PBDE congeners were synthesized and characterized. Physicochemical parameters including melting points and UV, 1 H NMR, and mass spectra are reported. Twenty-nine monobrominated to heptabrominated diphenyl ethers were synthesized by the coupling between four diphenyliodonium salts and nine phenolates. One tetrabromodiphenyl ether and two hexabromodiphenyl ethers were synthesized by bromination of two different PBDEs. Twenty-one of the PBDEs and two of the iodonium salts, 2,2′,4,4′-tetrabromodiphenyliodonium chloride and 3,3′,4,4′tetrabromodiphenyliodonium chloride, are to the authors' knowledge described for the first time. These synthesized reference compounds will aid in the identification and quantification of PBDEs present in environmental samples and will allow further assessment of PBDE toxicity.
Gas chromatography and mass spectrometry of methoxylated polybrominated diphenyl ethers (MeO-PBDEs)
Journal of Mass Spectrometry, 2006
Twenty-six methoxylated polybrominated diphenyl ethers (MeO-PBDEs) were characterized by gas chromatography (GC) on four different GC columns with different lengths and polarities, as well as by mass spectrometry using three ionization techniques, electron ionization (EI), electron capture negative ionization (ECNI) and positive ion chemical ionization (PICI). MeO-PBDE congeners with similar retention times on a nonpolar GC column were separated when analyzed on a polar GC column. EI can be used to determine the position of the methoxy substituent (ortho, meta or para) relative to the diphenyl ether oxygen in the MeO-PBDEs. The PICI ionization technique is shown to be valuable to generate structural information of the MeO-PBDEs, i.e. the degree of bromination on both the methoxy-substituted ring and the entirely brominated phenyl ring can be obtained. This structure information can also be achieved for certain MeO-PBDEs with the methoxy group in ortho position to the diphenyl ether bond in ECNI mode. Like other brominated compounds ECNI is preferable when analyzing environmental samples for quantification of MeO-PBDEs because of the formation of bromide ions, which enables low detection limits.
Analytical Chemistry, 2009
A total of 14 tetra-to deca-PBDE congeners were separated on a C 18 reversed phase liquid chromatographic column. PBDEs 47, 85, 99, 100, 153, 154, 183, 196, 197, 203, 206, 207, 208, and 209 were eluted using a gradient methanol/water/toluene mobile phase system at a flow rate of 0.5 mL min -1 . 13 C-BDE-47, 13 C-BDE-99, 13 C-BDE-153, BDE-128, and 13 C-BDE-209 were used as internal standards, while 13 C-BDE-100 was used as a syringe standard. Separated analytes were ionized using an atmospheric pressure photoionization (APPI) source equipped with a 10 eV krypton lamp and operated in negative ion mode. [M-Br + O]ions were monitored as precursor ions for all studied PBDEs, except for BDE-208 and BDE-209 which produced higher intensity at the [C 6 Br 5 O]ion cluster.