Laser‐based radiocarbon detection in the laboratory: How soon?

Abstract

Research over the past 25 years and the use of accelerator mass spectrometry (AMS) have demonstrated benefits of single‐atom counting of 14C compared with scintillation monitoring of 14C radioactive decay for a multitude of applications in drug development studies. These include pharmacokinetics and metabolism studies, microdosing studies, and quantification of DNA adducts. In the last decade, the possibility of single‐atom counting using lasers has been demonstrated, providing the possibility of simplified laboratory‐based systems, which can equal or excel AMS sensitivity and provide scintillation system convenience without high levels of radioactivity. To achieve the required sensitivity, optical storage cavities have been used to enhance the laser interaction of the low densities of radiocarbon present. Two types of laser technologies have been used‐cavity ring‐down spectroscopy (CRDS) and intracavity opto‐galvanic spectroscopy (ICOGS). Problems to be overcome to achieve routine use have included separation of the 14C signal from backgrounds, achievement of acceptable precision and accuracy, reduction of measurement times for small samples, and improvement in the ease of use for the operator. Both technologies have achieved impressive results to date using samples of order 1 mg with CRDS and 10 μg with ICOGS. Commercial development is the next step.

Online Biogenic Carbon Analysis Enables Refineries to Reduce Carbon Footprint during Coprocessing Biomass- and Petroleum-Derived Liquids

“…This method works with a fixed frequency stabilized 14 CO 2 laser and combines four different techniques previously studied: laser assisted ratio analyzer (LARA), optogalvanic spectroscopy, optical impedance spectroscopy and laser intracavity absorption spectroscopy . A later study was able to replicate these initial results and resolve issues found by other authors around the repeatability of the results and the absorption background due to 13 CO 2 and 12 CO 2 . ,− It was demonstrated that a precision of 1% is achievable by ICOGS with a few minutes of analysis, although calibration can be challenging . The main advantage of SCAR, CRDS, and ICOGS optical techniques for 14 C detection is the possibility of real-time analysis.…”

“…Optical and laser techniques for 14 C detection and quantification have been proposed as advanced methods for measuring biogenic carbon. 104,105 Optical detection of carbon isotopes, such as 14 C, has shown some issues, especially when high precision and low limits of detection are required. A limitation being susceptibility of spectroscopic detectors to physical interference from background signals, thus, requiring chemical or physical sample preparation to improve precision.…”

“…117,119−121 It was demonstrated that a precision of 1% is achievable by ICOGS with a few minutes of analysis, although calibration can be challenging. 105 The main advantage of SCAR, CRDS, and ICOGS optical techniques for 14 C detection is the possibility of real-time analysis. Samples need to be oxidized to CO 2 that can be further directed to the optical isotope spectrometer; thus, direct online measurement of refinery unit outputs are possible with limited sample preparation and potentially preconcentration.…”