John T.G. Hamilton David B. Harper Laurence G. Miller Clare Lamb James T. Kennedy Angela Downey Sean McCauley Allen H. Goldstein Robert M. Kalin 2001 <p><span>Gas chromatography/mass spectrometry/isotope ratio mass spectrometry (GC/MS/IRMS) methods for &delta;</span>¹³<span>C measurement of the halomethanes CH</span>₃<span>Cl, CH</span>₃<span>Br, CH</span>₃<span>I and methanethiol (CH</span>₃<span>SH) during studies of their biological production, biological degradation, and abiotic reactions are presented. Optimisation of gas chromatographic parameters allowed the identification and quantification of CO</span>₂<span>, O</span>₂<span>, CH</span>₃<span>Cl, CH</span>₃<span>Br, CH</span>₃<span>I and CH</span>₃<span>SH from a single sample, and also the concurrent measurement of &delta;</span>¹³<span>C for each of the halomethanes and methanethiol. Precision of &delta;</span>¹³<span>C measurements for halomethane standards decreased (&plusmn;0.3, &plusmn;0.5 and &plusmn;1.3&permil;) with increasing mass (CH</span>₃<span>Cl, CH</span>₃<span>Br, CH</span>₃<span>I, respectively). Given that carbon isotope effects during biological production, biological degradation and some chemical (abiotic) reactions can be as much as 100&permil;, stable isotope analysis offers a precise method to study the global sources and sinks of these halogenated compounds that are of considerable importance to our understanding of stratospheric ozone destruction.&nbsp;</span></p> application/pdf 10.1002/rcm.219 en Wiley Continuous flow stable isotope methods for study of δ¹³C fractionation during halomethane production and degradation article