Establishment and application of total phenols content model of Chinese fir based on near-infrared spectroscopy

【Objective】Chemical determination of total phenol content in wood samples was time-consuming and complex. It was of great significance to establish a rapid non-destructive testing model for total phenol content in Chinese fir wood samples for non-destructive testing and wood decay prediction.【Method】In the experiment, 114 Chinese fir (Cunninghamia lanceolata) wood samples were taken as the research objects, and the total phenol content of the samples was determined by Folin phenol method. The MPA Fourier transform spectrometer was used to collect the diffuse reflectance spectrum data of Chinese fir wood. The wood samples were divided into correction set and verification set. Quantitative models of total phenol were established by different spectral pretreatment methods and modeling methods, and the optimal model was selected and verified by validation set.【Result】The variation range of total phenol content was large, which could be used to construct the near-infrared model. 114 Chinese fir wood samples were scanned by near-infrared spectroscopy, and the modeling spectral range was 9403.9-7498.4 cm^-1, 6102.1-5446.4 cm^-1 and 4605.5-4242.9 cm^-1. The near-infrared spectra of Chinese fir wood samples were pretreated, and the optimal combination was obtained:standard normal variable transformation(SNV) and first derivative, partial least squares regression(PLS) was used to establish the model. The determination coefficients of calibration set and cross validation set of total phenol content in Chinese fir wood samples were 0.8679 and 0.7549, respectively. The root mean square error of calibration(RMSEE) and root mean square error of cross validation(RMSECV) were 0.448 and 0.586, respectively, the values were small and close, indicating that the model had good stability. The root mean square error of prediction(RMSEP) and relative standard deviation (RPD) were 0.521 and 2.16, respectively, indicating that the model could be used for quantitative analysis.【Conclusion】It is feasible to detect the total phenol content of Chinese fir by near-infrared spectroscopy, which provides an effective and nondestructive method for the rapid determination of wood chemical components. Affected by the fitting rules, although the constructed model can not be used for accurate quantitative determination, it can still be used in daily scientific research and production detection. It has broad application prospects in wood material prediction and improved variety breeding.