Recent advances of chemometric calibration methods in modern spectroscopy: Algorithms, strategy, and related issues

In recent years, modern spectral analysis techniques, such as ultraviolet–visible (UV-vis) spectroscopy, mid-infrared (MIR) spectroscopy, near-infrared (NIR) spectroscopy, Raman spectroscopy, terahertz (THz) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, laser-induced breakdown spectroscopy (LIBS), etc., have experienced rapid development and have been widely applied in various fields such as agricultural, food, pharmaceutical, petroleum, chemical industry, tobacco, environmental protection and medical science. A remarkable feature of all these techniques is to extract useful chemical information from the spectral data as detailed as possible with the aid of chemometric methods with the aim of significantly improving both robustness and accuracy of analytical results. Under the general background of the development in artificial intelligence, big data, cloud computing, and other technologies, the emergence of novel idea, approaches, and strategies endows chemometrics with a new vitality. Chemometrics has become the research focuses and hotspots in various fields, especially in the field of spectral analysis. This article reviewed various chemometric methods applied in modern spectral analysis in recent ten years, especially from the perspective of practicability, including spectral pre-processing, wavelength (variable) selection, data dimension reduction, quantitative calibration, pattern recognition, calibration transfer, calibration maintenance, and multispectral data fusion. More importantly, future trends in chemometric methods in the field of spectral analysis was also prospected in this article. It is sincerely expected that this summary and review could give specialists and scholars in the fields of spectroscopy and chemometrics certain inspiration to accelerate modern spectral analysis techniques booming evolution.