Cavity ringdown spectroscopy of nitric oxide in the ultraviolet region for human breath test

Abstract

We report the spectrum of nitric oxide (NO) in the ultraviolet (UV) (225.4–227.0 nm) region based on cavity ringdown spectroscopy (CRDS). A cavity ringdown system, which consisted of a tunable UV laser source and a vacuum-pumped ringdown cavity, was constructed to measure NO at room temperature and atmospheric or reduced pressure. The measured spectra were validated using LIFBase simulations. The absorption cross-section of NO at the strongest absorption peak at 226.255 nm was measured to be 7.64 × 10−18 cm2 molecule−1. Using the measured mirror reflectivity of 99.55% at 226.255 nm, the detection limit of NO was determined to be 7.4 ppb (parts per billion) based on the standard 3-σ criteria. The stability and reproducibility of this CRDS system were also tested. Furthermore, exhaled gas samples from 203 human subjects (105 healthy people and 98 lung cancer patients) were measured using the system. Results demonstrated that the cavity ringdown spectroscopy in the deep-UV region has potential for breath NO test.

Combined Experimental and Computational Kinetics Studies for the Atmospherically Important BrHg Radical Reacting with NO and O2

“…The HgBr 2 concentration was 6 × 10 12 molecule cm –3 , extrapolated from the literature data using the Clausius–Clapeyron equation. NO gas (Airgas, 2534 ppm in N 2 with the NIST-certified accuracy of ≤1%) was purified using an Ascarite trap (Sigma-Aldrich) and characterized by UV–vis spectroscopy . The absence of impurities, e.g., NO 2 , was verified by capturing the UV–vis absorption spectrum of the gas mixture from 192 to 660 nm.…”

Measurement of Exhaled Nitric Oxide in 456 Lung Cancer Patients Using a Ringdown FENO Analyzer

“…Fluorinated ethylene propylene (FEP) bags (1 L, Beijing HCTC Environmental Protection Technology Ltd., Beijing, China) were used to collect off-line breath samples. Previously, we proved that FEP bags can store standard NO gas diluted by nitrogen for 5 h without significant changes [43]. In this study, each subject remained in a sitting position for approximately 3 min and then provided one breath sample (>0.7 L) in a sitting position through a disposable mouthpiece between 10 and 15 s, without using a nose-clip, in accordance with the recommendations from the European Respiratory Society and the American Thoracic Society [44,45].…”

“…The background-subtraction method was used to determine the exhaled NO level in breath samples. This method is described in detail in our previous work, the exhaled NO level can be determined from a difference in the absorbance between a selected peak and the background baseline [43]. The wavelength of 226.255 nm was chosen as the most suitable wavelength to detect exhaled NO because many VOCs in the breath, such as acetone and isoprene, absorb radiation with a wavelength of 226 nm.…”

“…Comparison of the testing results shows that this ringdown breath acetone analyzer can be used for reliable online, real-time clinic testing. The overall structure, working principle and system performance of the experimental device are described in detail in our previous work [43], and this device has been previously validated and demonstrated to be reliable and advantageous. The system has a lower detection limit of 7.4 ppb, and the baseline stability of the system is 0.52%, with good repeatability, stability and real-time performance.…”

Cavity Ring-Down Spectroscopy: Recent Technological Advancements, Techniques, and Applications

“…In a recent study, Ai et al 204 reported a CRDS instrumentation operating in the spectral region of deep-UV for the measurement of NO in human exhaled breath. The UV spectral region is particularly advantageous for human breath analysis being absolutely free from the absorption of water which is a major interfering constituent present in exhaled breath.…”