Compound‐specific hydrogen isotope analysis of fluorine‐, chlorine‐, bromine‐ and iodine‐bearing organics using gas chromatography–chromium‐based high‐temperature conversion (Cr/HTC) isotope ratio mass spectrometry

Rationale Compound‐specific isotope analysis (CSIA) is a valuable tool in environmental chemistry and in other fields of science. Currently, hydrogen CSIA of polar compounds containing exchangeable hydrogen is uncommon. To extend the scope of CSIA applications, we present an alternative method of analysis, bypassing the typical step of derivatization. The method is demonstrated for two environmental contaminants, 4‐bromophenol (4BP) and 2,4,6‐tribromophenol (TBP). Methods Net isotope ratios obtained by CSIA combine the isotope composition of nonexchangeable, carbon‐bound hydrogen and the exchangeable hydroxyl hydrogen. To constrain the isotope composition of the latter, an ethyl acetate solution of 4BP or TBP injected into the IRMS instrument was amended with excess water of known isotope composition. The results were calibrated using bracketing control samples analyzed in sequence with the unknown samples and the known isotope ratios of water present in ethyl acetate solution. Results The analytical precision was comparable to the precision for halogenated compounds without exchangeable hydrogen, analyzed using similar instrumentation. The isotope ratios of the bromophenols correlated with the isotope composition of the water in the sample matrix, suggesting that the hydroxyl group of the target compound remained close to the equilibrium with the sample water during the passage through the instrument. Based on this relationship, the signatures of the nonexchangeable hydrogen were obtained using the isotope composition of sample water as the proxy for the isotope composition of the target compound hydroxyl group. Conclusions The developed method could be adopted to analysis of other low molecular weight compounds amenable to gas chromatography without the absolute need for derivatization. Currently, the method can be used for samples from laboratory experiments, with high concentrations of the target compound to provide mechanistic insight into the degradation mechanisms. Further work would be required to optimize the method to low concentration environmental samples.

Section: Resultssupporting

confidence: 68%

Section: Analytical Precision Accuracymentioning

confidence: 99%

Derivatization‐free method for compound‐specific isotope analysis of nonexchangeable hydrogen of 4‐bromophenol

Kuder

Bernstein

Gelman

2019

“…However, at the moment this method is only applicable for single isotope analysis. The isotope composition of other elements such as chlorine, bromine or hydrogen, which may reveal interesting insights into reaction mechanisms, can at the moment only be analyzed after derivatization by GC/Cr/HTC‐IRMS or GC/ICP‐MS …”

Section: Discussionmentioning

confidence: 99%

“…Moreover, 1 nmol C has to be injected for halogenated benzoates to yield stable isotope ratios by this LC/IRMS method, whereas the sensitivity limits for GC/IRMS are described as 0.1-5 nmol. 32 Whereas no significant isotopic fraction was visible for 4-Cl-benzoate, 3-Cl-benzoate and 3-Br-benzoate reveal significant inverse carbon isotopic fractionation moment only be analyzed after derivatization by GC/Cr/HTC-IRMS 33 or GC/ICP-MS. 34,35…”

Section: Discussionmentioning

confidence: 99%

Liquid chromatography/isotope ratio mass spectrometry analysis of halogenated benzoates for characterization of the underlying degradation reaction in Thauera chlorobenzoica CB‐1^T

Franke

Kümmel

Nijenhuis

2018

“…16,[19][20][21] However, the use of concentrated acids in conventional wet digestion methods results in digests with high residual acidity, causing the formation of volatile bromine and iodine species. [1][2][3][4]17,22 Extraction methods using alkaline solutions can avoid the formation of the volatile species, but the high carbon content in the final solution can impair the determination step, including ICP-MS analysis. [1][2][3][4]17 Microwave-induced combustion (MIC) is an excellent alternative as a sample preparation method for further determination of bromine and iodine.…”

Section: Introductionmentioning

confidence: 99%

Feasibility of microwave‐induced combustion combined with inductively coupled plasma mass spectrometry for bromine and iodine determination in human nail

Novo

Henn

Flores

et al. 2020

Rationale Bromine and iodine have important physiological functions; however, in inadequate concentration, they can also cause several physiological problems. Their mobility assessment in human organisms through biological sampling may help clarify some doubts related to metabolic routes, which are still not well elucidated. In this context, a suitable analytical method for this purpose should be developed. Methods An analytical method for determining ultratrace levels of bromine and iodine in human nail samples was developed. Inductively coupled plasma mass spectrometry (ICP‐MS) using a conventional nebulization system was immediately chosen as the determination tool because of its powerful sensitivity and selectivity. Sample preparation methods including microwave‐induced combustion (MIC), microwave‐assisted extraction, and microwave‐assisted digestion were evaluated. The compatibility of the final solutions with ICP‐MS analysis was considered while the method was developed. Results MIC was chosen as the most suitable method for the sample preparation for determining the levels of bromine and iodine in human nail samples using ICP‐MS. Unlike other sample preparation methods, this one fully eliminated interferences related to the carbon content and memory effects. Sample masses up to 100 mg were efficiently digested, and the analytes were quantitatively absorbed using only 50 mmol L−1 NH4OH solution. Recoveries ranged from 93% to 102%, and the relative standard deviation was < 8%. Conclusions The proposed analytical method presents important characteristics for routine analysis. It allows ultratrace determination even when low sample masses are used because of the low blank values, reduced volume of reagents, and powerful detectability using ICP‐MS.