Résumé
Open-path Fourier transform infrared ( OP/FT-IR) spectra were analyzed with target factor analysis ( TFA) and band-target entropy minimization ( BTEM) respectively, with the purpose to reconstruct spectral characteristics of target molecules from matrices of spectra. Five sessions of continuous OP/FT-IR monitoring were carried out around farms. For each session, the spectra were arranged row-wisely in order of measuring time, which yielded five matrices for data analysis. Results showed that both BTEM and TFA could reconstruct spectral characteristics of target molecules from the spectral data matrix, but the performance of the two methods differed slightly. TFA can retrieve spectral features of target molecules in the presence of interferences, and the reconstructed spectra are similar to corresponding reference. BTEM can implement such spectral retrieval without the reference spectrum. This work presents not only the application of BTEM method to qualitative analysis for OP/FT-IR spectra, but also a thorough comparison between the two methods. The conclusion is helpful to qualitative analysis of complex multi-component systems.