Clumped isotope measurements on nanomoles of CO 2 using a hollow core fiber-based spectrometer
Year: 2025
Type: article
Abstract: The abundance of carbon dioxide (CO 2 ) clumped isotopologues is an important tracer of environmental conditions in both atmospheric and paleoclimatic contexts. However, the conventional method for accurate CO 2 clumped isotope measurements, based on magnetic sector isotope ratio mass spectrometers (IRMSs), is time-consuming (hours per replicate) and requires large sample sizes (up to 100 µmoles CO 2 ). The recent development of isotope ratio laser spectrometers (IRLSs) determines CO 2 clumped isotope composition based on the infrared absorption spectra of corresponding CO 2 isotopologues and has significantly decreased the duration of clumped isotope measurements (minutes per replicate). However, existing IRLS instruments still require similar sample sizes to current IRMSs. Here, we present, to the best of our knowledge, a new IRLS prototype that demonstrates the feasibility of performing clumped isotope measurements using only nanomoles of CO 2 . The instrument leverages hollow core fiber (HCF) technology and achieves a reduction in sample size of about four orders of magnitude compared to existing IRLSs. We successfully detect and quantify the clumped isotopologues 16 O 13 C 18 O and 18 O 12 C 18 O absorption using ∼17 nanomoles of CO 2 and measure their abundances to precisions of 0.7‰ and 1.0‰, respectively in 1-1.5 minutes. Combining them with three other measured isotopologue lines we are able to calculate the clumped isotope ratios Δ 638 and Δ 828 , achieving precisions of 0.7‰ and 1.8‰ in 15-30 seconds. Our results demonstrate the potential of HCF technology for clumped isotope analyses of nanomoles of CO 2 with future technical improvements particularly in mid-infrared fiber technology.
Source: Optics Express
DOI: 10.1364/oe.582189
Institution: Woods Hole Oceanographic Institution
Language: English
Subfield: Spectroscopy
Field: Chemistry
Domain: Physical Sciences
SDG: Climate action
Open Access status: gold
Estimated APC paid: $2,270
OpenAlex ID: W4416614182