Compound-specific carbon isotope analysis for mechanistic characterization of debromination of decabrominated diphenyl ether

Xifen Zhu; Yin Zhong; Heli Wang; Dan Li; Yirong Deng; Shutao Gao; Ping'an Peng

doi:10.1002/rcm.8758

Compound-specific carbon isotope analysis for mechanistic characterization of debromination of decabrominated diphenyl ether

Rapid Commun Mass Spectrom. 2020 Jun 15;34(11):e8758. doi: 10.1002/rcm.8758.

Authors

Xifen Zhu^{1

2}, Yin Zhong¹, Heli Wang^{1

2}, Dan Li^{1

2

3}, Yirong Deng^{1

2

4}, Shutao Gao¹, Ping'an Peng¹

Affiliations

¹ Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, State Key Laboratory of Organic Geochemistry, Guangzhou, 510640, China.
² University of Chinese Academy of Sciences, Beijing, 100049, China.
³ School of Environment and Civil Engineering, Dongguan University of Technology, Dongguan, 523808, China.
⁴ Guangdong Provincial Academy of Environmental Science, Guangdong Key Laboratory of Contaminated Sites Environmental Management and Remediation, Guangzhou, 510045, China.

PMID: 32065465
DOI: 10.1002/rcm.8758

Abstract

Rationale: Decabrominated diphenyl ether (BDE-209) is a notorious persistent organic pollutant widely found in the environment. Developing a compound-specific isotope analysis (CSIA) method is much needed in order to trace its transport and degradation processes and to evaluate the effectiveness of the remediation of BDE-209 in the environment. However, the conventional CSIA method, i.e. gas chromatography (GC) combustion isotope ratio mass spectrometry, is not appropriate for BDE-209 because of its high thermal instability and incomplete combustion.

Methods: We developed a high-performance liquid chromatography (HPLC) method for the separation and purification of BDE-209 that prevents its thermal reactivity as occurred in prior GC-based methods. The δ¹³ C value of the purified BDE-209 was determined using offline elemental analyzer isotope ratio mass spectrometry (EA/IRMS). This two-step method was applied to determine the δ¹³ C values of BDE-209 in two commercial samples and to characterize carbon isotope fractionation associated with the debromination of BDE-209 via nanoscale zero-valent iron.

Results: The mean values of daily δ¹³ C analyses of six replicates of a BDE-209 standard varied from -27.66‰ to -27.92‰, with a standard deviation ranging from 0.07‰ to 0.16‰, indicating a good reproducibility of EA/IRMS. The EA/IRMS analysis of the purified BDE-209 standard indicated no obvious isotope fractionation during the sample purification. The impurity content in commercial BDE-209 samples may contribute additional variation of the δ¹³ C values of BDE-209. The δ¹³ C values of BDE-209 gradually changed from -27.47 ± 0.37‰ to -24.59 ± 0.19‰ when 74% of the BDE-209 standard was degraded within 36 h. The estimated carbon isotope enrichment factor was -1.72 ± 0.18‰.

Conclusions: The two-step method based on HPLC and EA/IRMS avoids the thermal instability of BDE-209 in the traditional CSIA method. It offers a novel approach for elucidating the degradation mechanisms of BDE-209 in the environment and for source identification in contaminated sites.

Abstract

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