Simultaneous Sensitive Determination of δ13C, δ18O, and δ17O in Human Breath CO2 Based on ICL Direct Absorption Spectroscopy.

Ligang Shao,Tu Tan,Xiaoming Gao,Guishi Wang,Jiaoxu Mei,Jiajin Chen,Kun Liu

doi:10.3390/s22041527

Abstract

Previous research revealed that isotopes 13C and 18O of exhaled CO2 have the potential link with Helicobacter pylori; however, the 17O isotope has received very little attention. We developed a sensitive spectroscopic sensor for simultaneous δ13C, δ18O, and δ17O analysis of human breath CO2 based on mid-infrared laser direct absorption spectroscopy with an interband cascade laser (ICL) at 4.33 μm. There was a gas cell with a small volume of less than 5 mL, and the pressure in the gas cell was precisely controlled with a standard deviation of 0.0035 Torr. Moreover, real-time breath sampling and batch operation were achieved in gas inlets. The theoretical drifts for δ13C, δ18O, and δ17O measurement caused by temperature were minimized to 0.017‰, 0.024‰, and 0.021‰, respectively, thanks to the precise temperature control with a standard deviation of 0.0013 °C. After absolute temperature correction, the error between the system responded δ-value and the reference is less than 0.3‰. According to Allan variance analysis, the system precisions for δ13C, δ18O, and δ17O were 0.12‰, 0.18‰, and 0.47‰, respectively, at 1 s integration time, which were close to the real-time measurement errors of six repeated exhalations.

Highlights

Academic Editors: Thomas Geernaert, Breath analysis, which is a non-invasive and painless method, has been proven to have potential for disease screening and diagnosis [1–5]
Exhaled CO2 is usually a product of glucose catabolism in the human body, and previous research revealed that carbon-13 (13 C) in breath CO2 has a potential link with the gastric pathogen Helicobacter pylori (H. pylori) in response to glucose ingestion [6,7]
A few studies have reported that the oxygen-18 (18 O) isotopes in exhaled CO2 are a biomarker related to H. pylori because of the rapid exchange of the 16 O in 12 C16 O2 and 18 O in H2 18 O in response to periplasmic α-carbonic anhydrase activity [13–15]

Summary

Introduction

Academic Editors: Thomas Geernaert, Breath analysis, which is a non-invasive and painless method, has been proven to have potential for disease screening and diagnosis [1–5]. Carbon dioxide (CO2 ) is one of the most important components in human exhaled substance, accounting for about. Exhaled CO2 is usually a product of glucose catabolism in the human body, and previous research revealed that carbon-13 (13 C) in breath CO2 has a potential link with the gastric pathogen Helicobacter pylori (H. pylori) in response to glucose ingestion [6,7]. A few studies have reported that the oxygen-18 (18 O) isotopes in exhaled CO2 are a biomarker related to H. pylori because of the rapid exchange of the 16 O in 12 C16 O2 and 18 O in H2 18 O in response to periplasmic α-carbonic anhydrase activity [13–15]

Methods

Findings

Discussion

Conclusion