In this paper we discuss different methods of narrow spectral line shape measurements for a wide spectral range by means of high-resolution spectrometers such as the Fabry-Perot spectrometer, Zeeman spectrometer and Fourier transform spectrometer as well as a theoretical model for spectral line shape modelling and solving of the inverse task based on Tikhonov's regularization method. Special attention is devoted to the line shape measurements for the optically thin light sources filled with Hg, Ar, Xe, Kr for their use in high precision analysers for detection of heavy metals and benzene