An Approach for Assessing Total Instrumental Uncertainty in Compound-Specific Carbon Isotope Analysis:  Implications for Environmental Remediation Studies

Abstract

Determination of compound-specific carbon isotope values by continuous flow isotope ratio mass spectrometry is impacted by variation in several routine operating parameters of which one of the most important is signal size, or linearity. Experiments were carried out to evaluate the implications of these operating parameters on both reproducibility and accuracy of delta13C measurements. A new method is described for assessing total instrumental uncertainty of routine compound-specific delta13C analysis, incorporating both accuracy and reproducibility. These findings have important implications for application of compound-specific isotope analysis in environmental geochemistry and in particular for the rapidly developing field of isotopic investigation of biodegradation and remediation of organic chemicals in contaminant hydrogeology.

A model-based assessment of the potential use of compound-specific stable isotope analysis in river monitoring of diffuse pesticide pollution

“…The magnitude of the simulated enrichment between the source area and the hillslope outlet in scenario 1 exceeds the uncertainty range of CSIA. Isotope ratios increased by 4 ‰ for δ 13 C and by 20 ‰ for δ 2 H, while the instrumental uncertainty is about 0.5 ‰ for carbon and 5 ‰ for hydrogen isotope analysis (Sherwood Lollar et al, 2007). This indicates that the enrichment in the isotopic composition at the hillslope outlet relative to the source values is detectable, which supports the use of CSIA in the analysis of diffuse river pollution under average hydrological conditions.…”

Linking Low-Level Stable Isotope Fractionation to Expression of the Cytochrome P450 Monooxygenase-Encoding ethB Gene for Elucidation of Methyl tert -Butyl Ether Biodegradation in Aerated Treatment Pond Systems

“…As shown in Fig. 4a, the difference of ␦ 13 C rarely exceeded the total analytical uncertainty Ϯ 0.5‰ (47) and never left the typical range of ␦ 13 C values for MTBE in gasoline (Ϫ28.3‰ to Ϫ31.6‰) (22,48).…”

Fractionation in position-specific isotope composition during vaporization of environmental pollutants measured with isotope ratio monitoring by 13C nuclear magnetic resonance spectrometry

“…This issue has been addressed by several authors, either in reviews or during the interpretation of their results (Elsner et al, 2012;Hofstetter and Berg, 2011;Jeannottat and Hunkeler, 2012;Sherwood Lollar et al, 2007;Thullner et al, 2012). Slater was among the first to point out that a Dd 13 C value lower than~1‰ (with the standard deviation of that time, 2003) should lead to non-significant enrichment factors (Slater, 2003).…”