Anaerobic transformation of a technical brominated diphenyl ether mixture by super-reduced vitamin B12 and dicyanocobinamide

Abstract

The anaerobic transformation of the technical octabromo diphenyl ether mixture, DE-79, was investigated by incubation with two super-reduced corrinoids, dicyanocobinamide and cyanocobalamin (vitamin B12). The transformation produced 33 brominated diphenyl ethers (BDEs), 23 of which could be assigned to known structures. Within 1 d, the hepta- to nona-BDEs in DE-79 were almost quantitatively transformed with dicyanocobinamide to lower-brominated homologs. Along with the decrease of high-brominated congeners, concentrations of some tetra- to hexabromo congeners initially increased, followed by a decreasing or constant concentration during longer incubations. Super-reduced cyanocobalamin also was able to transform BDE congeners of DE-79. Whereas the transformation rates of hepta- to nona-BDEs of DE-79 by both corrinoids were comparable, tri- to hexa-BDEs were susceptible to further transformation by super-reduced cyanocobalamin. Incubation of DE-79 with either corrinoid produced significant amounts of BDE 49. Because this congener is found in small quantities in both penta- and octabromo technical BDE mixtures, it may be a suitable indicator for reductive debromination of higher-brominated BDEs. Isolated BDE 196 was incubated as well with super-reduced dicyanocobalamine. After 1 d, 13 BDEs could be detected, with BDE 153, BDE 100, and BDE 99 dominating. After 7 d, only tetra-BDEs or lower-brominated BDEs were detectable. It could be shown that reductive debromination by super-reduced corrinoids is a possible source for lower-brominated BDEs (i.e., BDE 47, BDE 99, BDE 153, and BDE 154). The patterns observed with our bench-scale study design demonstrate that anaerobic transformation in the presence of reducing agents can help to explain the occurrence of environmentally relevant BDE congeners (e.g., BDE 47, BDE 99, and BDE 153).

Thorough analysis of polyhalogenated compounds in ray liver samples off the coast of Rio de Janeiro, Brazil

“…(Dorneles et al 2009). However, comparably high concentrations of BDE 49 have been suggested as a marker for the hydrodebromination of highly brominated PBDEs found in technical octaBDE (Gaul et al 2006). Especially the ratio of BDE 49/BDE 47 was shown to increase upon hydrodebromination of highly brominated congeners (Gaul et al 2006).…”

“…However, comparably high concentrations of BDE 49 have been suggested as a marker for the hydrodebromination of highly brominated PBDEs found in technical octaBDE (Gaul et al 2006). Especially the ratio of BDE 49/BDE 47 was shown to increase upon hydrodebromination of highly brominated congeners (Gaul et al 2006). Although BDE 183, the predominant congener in technical octaBDE, was not detected in any ray sample, it still appears that at least to some extent, the PBDE residues also originated from the previous use of octaBDE which undergoes hydrodebromination in the environment.…”

Identification and quantification of products formed via photolysis of decabromodiphenyl ether

“…The environmental occurrence of PBDEs is dominated by tetraBDEs-hexaBDEs as a primary consequence of PentaBDE uses and due to their unfavorable physicochemical characteristics (Law et al 2003;Hites 2004;de Wit et al 2006;Law et al 2006). Both OctaBDE and DecaBDE products are discussed as potential sources of the lower brominated diphenyl ethers (He et al 2006;Gaul et al 2006). , making up as much as 92-98% of the PBDE congeners in DecaBDE La Guardia et al 2006), is a significant contaminant in some river estuaries (Chen et al 2007b), in sediments (Moon et al 2007), and in air Gouin et al 2006).…”

Fractionation of technical octabromodiphenyl ether by countercurrent chromatography combined with gas chromatography/mass spectrometry and offline and online 1H nuclear magnetic resonance spectroscopy

“…Polybrominated diphenyl ethers (PBDEs) have been heavily used as flame retardants, which resulted in environmental contamination of concern [9]. Technical octabromodiphenyl ether (DE-79) is a mixture of several major and minor compounds, some of which are not structurally known [9][10][11][12]. For a detailed study, CCC fractions were subsequently analyzed by gas chromatography coupled with mass spectrometry (GC/MS) as well as proton magnetic resonance ( 1 H NMR) spectroscopy.…”