AMS-validated high-precision radiocarbon analysis of ¹⁴C-enriched environmental samples by laser spectroscopy

Area of Science:

• Environmental Science
• Nuclear Chemistry
• Analytical Chemistry

Background:

• Radiocarbon (¹⁴C) is crucial for nuclear environmental protection due to its significant dose contribution from the nuclear industry.
• Accurate measurement of ¹⁴C is essential in areas affected by ¹⁴C emissions.
• Current methods like accelerator mass spectrometry (AMS) and liquid scintillation counting (LSC) are effective but can be time-consuming or costly.

Purpose of the Study:

• To evaluate the potential of Saturated-absorption CAvity Ring-down (SCAR) spectroscopy as a novel method for ¹⁴C analysis.
• To compare the performance of SCAR with established techniques (AMS, IRMS) for measuring ¹⁴C in enriched samples.
• To demonstrate the applicability of SCAR for analyzing slightly ¹⁴C-enriched environmental and plant samples.

Main Methods:

• Combustion of ¹⁴C-enriched plant samples to produce CO₂ gas.
• Measurement of ¹⁴C/¹²C and ¹³C/¹²C isotope ratios using AMS, SCAR, and Isotope Ratio Mass Spectrometry (IRMS).
• Comparative analysis of results obtained from SCAR and AMS, including δ¹³C correction.

Main Results:

• SCAR technology reproduced AMS measurement results with a difference of less than 4% after δ¹³C correction.
• The SCAR method demonstrated sufficient accuracy and linearity for measuring ¹⁴C/¹²C ratios in plant samples ranging from 115 to 2600 pMC.
• This study is the first to measure subsamples of CO₂ gas from the same source using AMS, SCAR, and IRMS for comparative isotopic analysis.

Conclusions:

• SCAR offers a fast, reliable, and cost-effective alternative to AMS and LSC for ¹⁴C analysis, particularly for lightly labeled or slightly enriched samples.
• SCAR is suitable for nuclear environmental protection applications involving organic samples with ¹⁴C levels exceeding the natural environmental concentration (∼100 pMC).
• The findings support SCAR as a promising new tool for radiocarbon research and environmental monitoring.