[Study of net analyte signal with near-infrared spectra for quantitative analysis]

Near-infrared spectroscopy is a rapid, high-efficiency, non-destructive and low-cost analytical technique, which has found widespread use for quantitative and qualitative analysis. Because of the complex nature of NIR spectra, multivariate calibration model plays a key role in the spectroscopic analysis. Further understandings of the model can be helpful for optimizing the model's performance. This paper introduces a convenient definition of net analyte signal, which is one of the figures of merit charactering multivariate calibration model. The absorbance data of the glucose aqueous solution are used for the calculation of net signal and explanation of the qualitative relationships between net analyte signal of glucose and absorptivity coefficients of other components. Qualitative changes of net signal with the complexity of samples are also given. Finally a simple expression is proposed for estimating the prediction error of concentration, which is instructive for further study of the robustness and accuracy of the multivariate calibration model.