Tunable diode laser spectroscopy at 1.6 and 2 /spl mu/m for detection of Helicobacter pylori infection using /sup 13/C-urea breath test

Tunable diode laser spectroscopy has been applied to diagnosis of Helicobacter pylori by detecting the /sup 13/CO/sub 2/ to isotope ratio in human breath. A number of line pairs in the 1.6- and 2.0-/spl mu/m band suitable for isotope ratio detection has been investigated in terms of temperature and pressure stability of the detected isotope ratio. Two wavelength modulated diode laser absorption spectrometers (WMS), one in each band, were set up to find the detection limit in isotope abundance difference. Isotope ratio measurements have been performed on /sup 13/CO/sub 2/ enriched gases with isotope ratios calibrated against an isotope ratio mass spectrometer (IRMS). The agreement between the delta values measured with the WMS technique and the IRMS was excellent. Eight breath samples from otherwise healthy volunteers were simultaneously analyzed by IRMS and the present method for possible infection with Helicobacter pylori.