A new automated method for high?throughput carbon and hydrogen isotope analysis of gaseous and dissolved methane at atmospheric concentrations

Rationale The dual isotope ratio analysis, carbon (?13C value) and hydrogen (?2H value), of methane (CH4) is a valuable tracer tool within range areas scientific investigation, not least wetland ecology, microbiology, CH4 source identification the tracing geological leakages thermogenic in groundwater. Traditional methods collecting, purification, separating analysing for ?13C ?2H determination are, however, very time consuming, involving offline manual extractions. Methods Here we describe new gas chromatography, pyrolysis/combustion, mass spectrometry (IRMS) system automated analysis either dissolved or gaseous down to ambient atmospheric concentrations (2.0 ppm). Sample introduction via traditional XYZ autosampler, allowing helium (He) purging sparging water from suitable, airtight bottles. Results routinely achieves precision <0.3‰ values <3.0‰ values, based on long-term replicate an in-house CH4/He mix standard (BGS-1), corrected two externally calibrated reference gases at near methane. Depending upon concentration therefore bottle size, runs between 21 (140-mL bottle) 200 samples (12-mL exetainer) unattended run overnight. Conclusions This represents first commercially available IRMS step forward routine (and high-volume) environmental studies.