¹³CO 2 /¹²CO 2 ratio analysis in exhaled air by lead-salt tunable diode lasers for noninvasive diagnostics in gastroenterology

Abstract

An analyzer of 13C02/'2C02 ratio in exhaled air based on lead-salt tunable diode lasers is presented. High accuracy of the carbon isotope ratio detection in exhaled carbon dioxide was achieved with help ofvery simple optical schematics. It was based on the use of MBE laser diodes operating in pulse mode and on recording the resonance CO2 absorption at 4.2 inn. Special fast acquisition electronics and software were applied for spectral data collection and processing. Developed laser system was tested in a clinical trail aimed to assessment eradication efficiency in therapy of gastntis associated with Helicobacter pylon infection. Data on the '3C-urea breath test used for P.pylori detection and obtained with tunable diode lasers in the course of the trail was compared with the results of Mass-Spectroscopy analysis and histology observations. The analyzer can be used also for '3C02/'2C02 ratio detection in exhalation to perform gastroenterology breath tests based on using other compounds labeled with stable isotopes.Keywords: tunable diode laser spectroscopy, '3C02/'2C02 ratio analysis, breath test, noninvasive diagnostics in gastroenterology, assessment ofthe Helicobacterpylori infection and eradication.