Tunable diode lasers application for fully automated absolute measurements of CO and CO2 concentrations in human breath

Measurements of carbon monoxide and carbon dioxide concentrations by registration of high resolution absorption spectra are described. A fully automated diode laser system developed to simultaneously measure CO and CO 2 , with sensitivity for CO up to 50 ppb and CO 2 up to 0.1 vol%, is described. Calculation of CO and CO 2 concentrations was carried out on the base of a priori date on strength and broadening coefficients of detected absorption lines. Test procedures of such diode laser systems are described. Possible reasons affected on accuracy and reliability of obtained data (e.g., the value of diode lasers spontaneous radiation, the stability of CO content in a cell, etc.) for absolute and relative calibration procedure are discussed. The physiological level of CO concentration in the breath of non smokers and smokers under different ambient conditions of CO concentrations in the atmosphere (in Moscow and in Maynooth) are compared. Recent results on statistical studies of the behavior of CO concentrations as a function of breath holding time are represented.