Application of Dual Carbon–Bromine Isotope Analysis for Investigating Abiotic Transformations of Tribromoneopentyl Alcohol (TBNPA)

Abstract

Many of polybrominated organic compounds, used as flame retardant additives, belong to the group of persistent organic pollutants. Compound-specific isotope analysis is one of the potential analytical tools for investigating their fate in the environment. However, the isotope effects associated with transformations of brominated organic compounds are still poorly explored. In the present study, we investigated carbon and bromine isotope fractionation during degradation of tribromoneopentyl alcohol (TBNPA), one of the widely used flame retardant additives, in three different chemical processes: transformation in aqueous alkaline solution (pH 8); reductive dehalogenation by zero-valent iron nanoparticles (nZVI) in anoxic conditions; oxidative degradation by H2O2 in the presence of CuO nanoparticles (nCuO). Two-dimensional carbon-bromine isotope plots (δ(13)C/Δ(81)Br) for each reaction gave different process-dependent isotope slopes (Λ(C/Br)): 25.2 ± 2.5 for alkaline hydrolysis (pH 8); 3.8 ± 0.5 for debromination in the presence of nZVI in anoxic conditions; ∞ in the case of catalytic oxidation by H2O2 with nCuO. The obtained isotope effects for both elements were generally in agreement with the values expected for the suggested reaction mechanisms. The results of the present study support further applications of dual carbon-bromine isotope analysis as a tool for identification of reaction pathway during transformations of brominated organic compounds in the environment.

Simultaneous observation of concurrent two-dimensional carbon and chlorine/bromine isotope fractionations of halogenated organic compounds on gas chromatography

“…Therefore, the bond energy difference between bond-0 and bond-1 is slightly larger than that between bond-0 and bond-2. As a result, the bond length difference between bond-0 and bond-1 is slightly bigger than that between bond-0 and bond-2, suggesting the molecular volume variation between 12 C 35 Cl and 13 C 35 Cl is greater than that between 12 C 35 Cl and 12 C 37 Cl. We accordingly conclude that substitution of a 12 C atom with a 13 C atom on an organochlorine molecule can cause larger molecular volume change relative to substitution of a 35 Cl atom with a 37 Cl atom.…”

“…We take CCl, a chlorinated methylidyne radical [41], for an imaginary example to elucidate the liquid-vapor isotope effects. We define the chemical bonds 12 C- 35 Cl, 13 C- 35 Cl, and 12 C- 37 Cl as bond-0, bond-1, and bond-2, respectively. According to the equations addressed in a previous study [42], we obtain the following modified equations: 35 (13) where v0, v1, and v2 are the vibrational frequencies of bond-0, bond-1, and bond-2, respectively; △v1 is the difference of the vibrational frequencies between v0 and v1, and △v2 is the difference of the vibrational frequencies between v0 and v2; m12, m13, m35 and m37 represent the atom masses of 12 C, 13 C, 35 Cl and 37 Cl, respectively.…”

Compound‐specific bromine isotope ratio analysis using gas chromatography/quadrupole mass spectrometry

“…During the last decades 13 C/ 12 C compound‐specific isotope analysis (CSIA) has been demonstrated as an effective analytical tool for assessing degradation of the environmental pollutants . Recently, the use of isotope analysis of two or more elements in the molecule has been proposed in order to obtain additional detailed information on the degradation mechanism of a particular compound . In studying the environmental fate of BOCs, 81 Br/ 79 Br‐CSIA can be used as a complementary tool for assessing the mechanism of BOCs bio/chemical transformations …”

“…[4,5] Recently, the use of isotope analysis of two or more elements in the molecule has been proposed in order to obtain additional detailed information on the degradation mechanism of a particular compound. [6][7][8][9][10][11][12][13] In studying the environmental fate of BOCs, 81 Br/ 79 Br-CSIA can be used as a complementary tool for assessing the mechanism of BOCs bio/chemical transformations. [10,14] Whereas 13 C/ 12 C-CSIA is already a robust analytical technique for environmental applications, implementation of 81 Br/ 79 Br-CSIA is still in the nascent stages.…”

“…[6][7][8][9][10][11][12][13] In studying the environmental fate of BOCs, 81 Br/ 79 Br-CSIA can be used as a complementary tool for assessing the mechanism of BOCs bio/chemical transformations. [10,14] Whereas 13 C/ 12 C-CSIA is already a robust analytical technique for environmental applications, implementation of 81 Br/ 79 Br-CSIA is still in the nascent stages. In the past, analytical methods for bromine isotope analysis using thermal ionization mass spectrometry (TIMS) [15] and isotope ratio mass spectrometry (IRMS) [16,17] were proposed for the isotope analysis of BOCs.…”