Development of Analytical Method for &lt;sup&gt;14&lt;/sup&gt;C Determination in Biomedical Sample by Laser Spectroscopy

Saito

et al. 2020

Jpn. J. Appl. Phys.

Self Cite

A linewidth reduction of a distributed feedback quantum cascade laser (DFB-QCL) based on optical feedback for a mid-infrared (MIR) cavity ring down spectroscopy (CRDS) 14C spectrometer is presented. A cat-eye reflector as well as a path-length enhancement by a Herriott cell were employed for a compact optical setup. The laser linewidth was evaluated by monitoring the beat frequency between the DFB-QCL and a MIR optical frequency comb (OFC). The linewidth reduction by optical feedback was clearly observed although slow frequency drifts caused by environmental changes were still visible. A low-bandwidth beat-note lock to the OFC was conducted for long-term stabilization as well as for precise frequency scanning and thereby 14C measurement by MIR CRDS with optical feedback was demonstrated successfully.

Section: Methodsmentioning

confidence: 99%

Mid-infrared cavity ring-down spectroscopy using DFB quantum cascade laser with optical feedback for radiocarbon detection

Saito

et al. 2020

Jpn. J. Appl. Phys.

Self Cite

“…Accelerator mass spectrometry (AMS) is a specific example and its ultra-high sensitivity leads the radiocarbon ( 14 C) in new applications such as carbon dating [1]. In drug development, so-called microdose studies or human phase-0 trials using 14 C have attracted conspicuous attention and are expected to make the drug development process more efficient [2]. The first microdose study demonstration in Japan was reported in 2010 by using AMS [3].…”

Section: Introductionmentioning

confidence: 99%

“…In this context, cavity ring-down spectroscopy (CRDS) using a fundamental vibration absorption line of carbon dioxide in 4.5 μm has been proposed as a substitute for AMS [4][5][6][7][8]. 14 C analysis based on CRDS especially designed for biomedical samples in microdose study has been developed [9]. In such a system, higher throughput and lower cost are required as well as high sensitivity sufficient for microdose studies (close to natural abundance of 14 C/C = 10 -12 ).…”

Section: Introductionmentioning

confidence: 99%

Background Noise Reduction in Mid-Infrared Cavity Ring-Down Spectroscopy for Radiocarbon Analysis

Proceedings of the Second International Symposium on Radiation Detectors and Their Uses (ISRD2018)

Tomita

et al. 2019

Self Cite

In cavity ring-down spectroscopy (CRDS), background noise caused by spurious reflective surfaces limits the sensitivity. This etaloning effect depends periodically on the laser frequency as well as the distance between the respective surfaces. In this work, Brewster spoiler is proposed as well as cavity temperature modulation. Suppression of baseline fluctuations in the system for 14 C analysis based on mid-infrared CRDS has been successfully demonstrated through several measurements of the spectrum baseline.

A cavity ring-down spectrometer for study of biomedical radiocarbon-labeled samples

Journal of Applied Physics

Tomita

et al. 2018

A compact cavity ring-down spectrometer aimed at the detection of trace amounts of radiocarbon (14C) in biomedical samples is demonstrated. Rapid sampling, as required for large scale studies, is made possible by modifications to a CHNS elemental analyzer. After conversion of the carbon content of a sample into CO2, spectral analysis using a high-finesse cavity in conjunction with a quantum cascade laser system reveals the ratio of 14CO2 in relation to the stable isotopologues of 12C and 13C. Cooling and temperature stabilization of the cavity is achieved by a combination of liquid cooling and thermo-electric elements. The system is studied in terms of reproducibility, linearity, and sensitivity as well as contamination and memory effects of the sampling process. While the performance of the system is still limited mainly due to etaloning and other systematic effects, first spectra of biomedical samples, such as urine and feces, have been analyzed at 14C concentration levels above ten times natural abundance. Results are compared with those from a traditional liquid scintillation counter system. Possibilities for improvement of the sensitivity are discussed.