Influence of temperature on synthetic data-based calibration models for low resolution open-path FTIR spectroscopy

This article presents the problem of determining the gas concentration under conditions of changing temperatures. The solution to this problem is based on spectral measurements using chemometric models. Such problems arise when measuring gases during various industrial processes, mainly the pyrolysis process. Chemometric models are built using synthetic calibration data. Line-by-line and statistical models were applied for spectra modelling. The effect of temperature on extracting the gas concentration from spectra of various resolutions was determined. Next, the global model was built and tested using calibration data for specific temperature ranges. The properties of the linear and nonlinear partial least-squares (PLS) models that were applied to the considered issues were demonstrated. CO and CH4 were used as example gases.