LAUSR

Abstract High-precision spectral analysis for complex liquid components has received much attention in recent years. However, the lack of systematic strategies of measurement and modeling notably appears when multiple internal and external factors vary—e.g., the sample parameters, instruments, and external environment. Many methods have been developed to eliminate these effects. According to the characteristics of error sources and its propagation rules, “M + N” theory integrates and classifies the internal and external factors that affect the analysis of complex liquid components into M factors and N factors systematically. “M” and “N” refers to the M components in a liquid and N interference factors, respectively, and “+” means that the spectral is a response to the interaction of M and N. In this review, “M + N” theory sums up five measurement and modeling strategies used to reduce the effect of various factors on spectral quantitative analysis of complex liquids. Finally, this review summarized the strategies used to improve the accuracy of quantitative analysis of complex liquids and discussed future research directions.