Laser-induced fluorescence spectroscopy of¹⁴N¹⁸O and its application to breath analysis

Abstract

Laser-induced fluorescence (LIF) spectroscopy is an efficient tool for the detection of low nitric oxide (NO) concentrations down to the parts per trillion (ppt) range. The isotopic selectivity of this method provides a broad potential of applications. . This transition has been used for an isotope specific online detection of 14 N 18 O from exhaled air. The detection limit for 14 N 18 O is 7.3 ± 1.8 ppt. With respect to 18 O-labelled drugs and amino acids this denotes a novel extension to NO research.

Breath Ammonia Analysis: Clinical Application and Measurement

“…Specific techniques used for ammonia quantification are laser induced fluorescence (LIF), cavity ring down spectroscopy (CRDS), tunable diode laser absorption spectroscopy (TDLAS), photoacoustic spectroscopy (PAS), and optical frequency comb cavity -enhanced absorption spectroscopy (OFC-CEAS). With LIF, detection of breath molecules as low as 10 ppt has been demonstrated with gases such as nitric oxide [69]. Recently, however, LIF has shown the capability for making qualitative measurements of ammonia [70].…”

Ultra-sensitive detection of nitric oxide isotopologues

“…A section of these measurements is displayed in figure 2. It could be shown that in certain areas of the spectra 15 N 16 O as well as 14 N 18 O can be observed without interference with the main compound 14 N 16 O [30]. Simulations for all three isotopologues have been performed with the program pgopher [32].…”

“…The combination of a 40 m 3 h −1 oil diffusion pump and a 150 L s −1 turbo molecular pump evacuates the spectrometer to a base pressure of 10 −6 mbar. A detailed description of the setup is given elsewhere [30].…”

Factors affecting improvement of fluorescence intensity of quartet and doublet state of NO diatomic molecule excited by glow discharge*

“…The potential energy curves of the lower lying level of NO diatomic molecule are constructed using the Rydberg-Klein-Rees (RKR) method with the help of the Bound program of Foth et al [30] Those states are X 2 Π, a 4 Π, A 2 Σ, B 2 Π, and b 4 Σ − . The essential spectroscopic constants required to construct the potential energy curves are cited from the literature [10,[16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] and are listed in Table 1.…”

“…[15] The fluorescence intensity spectra under applied electromagnetic waves with high resolution conduce to the understanding the electronic structure of NO molecule. [16][17][18] A prominent feature of the NO molecule is the fluorescence of the A 2 Σ-X 2 Π system by UV radiation in the atmosphere. [19] In addition, the observing of the emission spectrum of NO molecule by glow discharge excitation is an important tool for studying the chemistry of the atmosphere and the environmental pollution.…”