Improving the accuracy and sensitivity of 13C online detection in expiratory air using the TDLAS method in the spectral range of 4860–4880 cm−1

Implementing Kalman and Savitzky–Golay adaptive filters to process experimental signals and improve the sensitivity and accuracy of the measurements of the content of 13CO2 in human expiratory air with the tunable diode laser absorption spectroscopy method while using a laser diode as a tunable source in the range of 4860–4880 cm−1 near a wavelength of 2 µm has been reported. It is established that using these filters makes it possible to provide a detection sensitivity of 13CO2 at 5.5 1014 cm−3 with a minimum detectable fraction of 13CO2 in a mixture with 12CO2 of the order 2.1 10−5.