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Measurement of oxygen isotope ratios (18O/16O) of aqueous O2 in small samples by gas chromatography/isotope ratio mass spectrometry.
- Source :
- Rapid Communications in Mass Spectrometry: RCM; 3/30/2016, Vol. 30 Issue 6, p684-690, 7p
- Publication Year :
- 2016
-
Abstract
- Rationale Oxygen isotope fractionation of molecular O<subscript>2</subscript> is an important process for the study of aerobic metabolism, photosynthesis, and formation of reactive oxygen species. The latter is of particular interest for investigating the mechanism of enzyme-catalyzed reactions, such as the oxygenation of organic pollutants, which is an important detoxification mechanism. Methods We developed a simple method to measure the δ<superscript>18</superscript>O values of dissolved O<subscript>2</subscript> in small samples using automated split injection for gas chromatography coupled to isotope ratio mass spectrometry (GC/IRMS). After creating a N<subscript>2</subscript> headspace, the dissolved O<subscript>2</subscript> partitions from aqueous solution to the headspace, from which it can be injected into the gas chromatograph. Results In aqueous samples of 10 mL and in diluted air samples, we quantified the δ<superscript>18</superscript>O values at O<subscript>2</subscript> concentrations of 16 μM and 86 μM, respectively. The chromatographic separation of O<subscript>2</subscript> and N<subscript>2</subscript> with a molecular sieve column made it possible to use N<subscript>2</subscript> as the headspace gas for the extraction of dissolved O<subscript>2</subscript> from water. We were therefore able to apply a rigorous δ<superscript>18</superscript>O blank correction for the quantification of <superscript>18</superscript>O/<superscript>16</superscript>O ratios in 20 nmol of injected O<subscript>2</subscript>. Conclusions The successful quantification of <superscript>18</superscript>O-kinetic isotope effects associated with enzymatic and chemical reduction of dissolved O<subscript>2</subscript> illustrates how the proposed method can be applied for studying enzymatic O<subscript>2</subscript> activation mechanisms in a variety of (bio)chemical processes. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 09514198
- Volume :
- 30
- Issue :
- 6
- Database :
- Complementary Index
- Journal :
- Rapid Communications in Mass Spectrometry: RCM
- Publication Type :
- Academic Journal
- Accession number :
- 112900860
- Full Text :
- https://doi.org/10.1002/rcm.7481