Overcoming Challenges for Clumped Isotopes CO₂ Analysis on Carbonate Samples

Abstract:

Precision and accuracy on limited sample sizes are major challenges for clumped isotope analysis. Δ₄₇ determination from carbonate samples is significantly influenced by systematic drifts caused by laboratory temperature instability during measurement, and non-precise matching of crimping of the sample and reference capillaries, producing inaccurate data. This can now be overcome by using the Thermo Scientific™ LIDI 2 Software Workflow, where sample bracketing becomes possible based on software-controlled approach. Here we present the recent advances in clumped isotope analysis from small carbonate samples demonstrating the improvement in data precision and accuracy.

By applying the LIDI 2 method, sample bracketing is possible following a four-step approach, resulting in fully corrected temperature drift (i.e. eliminated from the data), decreasing the standard deviation by factor of 2. This is a substantial improvement for acquiring clumped isotope data as reaching a very stable temperature of ±0.1°C/h is a challenge for most laboratories. Alongside eliminating variation in the Δ₄₇ data caused by unstable laboratory air temperature, LIDI 2 also delivers perfect sample versus reference intensity matching, which results in significantly higher precision on each sample gas analyzed. Standard error of a single sample measurement is improved by up to factor of 2.

The LIDI 2 method delivers improved accuracy and precision on Δ₄₇ measurement from small Carbonate samples, which in combination with the latest advancements in inert capillaries coating and automated contaminant trapping contributes to enhanced clumped isotopes data quality.