Optimal wavelengths selection from all points for blood species identification based on spatially resolved near-infrared diffuse transmission spectroscopy

Abstract

Blood species identification is of great significance for forensic science, wildlife protection. In our previous research, we proved spatially resolved near-infrared transmission spectroscopy method was feasible and promising for non-contact blood species identification, including chicken, goat, macaque, pig and rat, with samples measured in the cuvettes. However, spatially resolved spectra may bring crosstalk between the contributing chromophores while increasing effective information. In this paper, we explored wavelength selection methods for spatially resolved transmission spectroscopy from two different views—selecting variables from wavebands of a single point (or position) and selecting variables from all wavebands of all points (or positions). Equidistant Combination Partial Linear Square (ECPLS) method was used for wavelength selection. Results showed that the PLSDA model built with the wavelengths selected by ECPLS methods from different view of points both had a better performance than the PLSDA model built with full wavebands. We further test the reliability of the wavelengths selected by ECPLS methods from different view of points with an external validation. The results indicated that variables selected from all points was more reliable than from single point, and also full wavebands. Moreover, the result can also direct the collection of spatially resolved spectra with proper scanning position. The overall results sufficiently demonstrate the PLSDA model constructed using selected wavelength variables by a proper wavelength variable method can be more effective and accurate. And the results can guide the design of the measurement system for spatially resolved spectroscopy.