| Molecular Spectroscopy is a means to obtain qualitative and quantitative information.Near-infrared spectroscopy belongs to the molecular spectroscopy,with its fast,non-destructive,extensive research object,etc.,is widely used in various fields.Kubelka-Munk theory is the basis quantitative theory of the diffuse reflectance spectroscopy of molecular spectroscopy.Kubelka-Munk theory has to do with the absorption coefficient k and the scatter coefficient s,of which the absorption coefficient k is related to the sample concentration,and the scatter coefficient is related to the particle size of sample.This paper used radix and Radix Scrophulariae as earrier,the near-infrared diffuse reflectance spectroscopy technique was applied,the quantitative theory Kubelka-Munk theory of near-infrared diffuse reflectance spectroscopy was the based on.The aim was to study the quantitative analysis of the Chinese herbal medicine using near-infrared diffuse reflectance.The mainly research contents are as follows:1.The quantitative analysis of differtent particle size distributions of Chinese herbal medicine using the near-infrared diffuse reflectance spectroscopyKubelka-Munk theory is related to the absorption coefficient k,and the k is related to the sample concentration,therefore,the effect of sample particle size on the measurement of lobetyolin in Codonopsis Radix and harpagoside in Radix Scrophulariae by near-infrared reflectance(NIR)spectroscopy was explored.The results showed that 90-125 ?m particle size distribution of Codonopsis Radix exhibited the best prediction ability with Rpre2=0.9115,RMSEP=0.0445 mg·g-1,and RPD=3.54,meanwhile,125-150 ?m particle size distribution of Radix Scrophulariae exhibited the best prediction ability with Rpre2=0.9513,RMSEP=0.1029 mg·g-1,and RPD=4.78.For the granularity-hybrid calibration model,the results showed that Codonopsis and were all in 90-180 ?m particle size distribution exhibited the best prediction ability with Rpre2=0.9087,RMSEP=0.0408 mg·g-1,and RPD=3.37 of Codonopsis Radix and Rpre2=0.8919,RMSEP=0.1632 mg·g-1,RPD=3.09 of Radix Scrophulariae.According to the relationship between the absoption A and k/s,when the scatter coefficient saw the same or the small range,the result of constructing model was more accurately.?.Particle size analysis of Chinese herbal medicine using the near-infrared diffuse reflectance spectroscopyThe scatter coefficient s of the Kubelka-Munk theory is related to the particle size,therefore,the measurement of particle size distribution D50?D10?D90 of Codonopsis Radix and Radix Scrophulariae by near-infrared reflectance(NIR)spectroscopy was explored.The different methods,such as PLS and LS-SVM,was comprared.The results showed that for the values of D50?D10 and D90 of Codonopsis Radix,RMSEP values of LS-SVM models were 12.4089?7.8850 and 21.1856,respectively.rPre values of LS-SVM models were 0.9947?0.9933 and 0.9938,respectively.RPD values of LS-SVM models were 9.6?8.0 and 9.0,respectively.However,RMSEP values of PLS models were 28.0970?17.6831 and 51.8493,respectively.rPre values of PLS models were 0.9730?0.9628 and 0.9630,respectively.RPD values of PLS models were 4.3?3.5 and 3.7,respectively.For the values of D50?D10 and D90 of Radix Scrophulariae,RMSEP values of LS-SVM models were 18.8386?7.8032 and 26.5565,respectively.rpre values of LS-SVM models were 0.9882?0.9894 and 0.9912,respectively.RPD values of LS-SVM models were 6.6?6.8 and 7.6,respectively.However,RMSEP values of PLS models were 39.3524?13.9807 and 59.8503,respectively.rpre values of PLS models were 0.9473?0.9646 and 0.9540,respectively.RPD values of PLS models were 3.1?3.8 and 3.4,respectively.Kubelka-Munk equation:f(R?)=k/s=?c/s=bc,b is related to the scatter coefficient,in addition,particle size affected the the scatter coefficient,which indicted that there was non-linear relationship between NIR spectroscopy and particle size.Meanwhile,the prediction ability of LS-SVM models were better than PLS models,which also confirmed that there was non-linear relationship between NIR spectroscopy and particle size.All the above results present guidance for the deternination of particle size in NIR analysis of Chinese traditional medicine.?.The evaluation of quantitative analysis of Chinese herbal medicine using the near-infrared diffuse reflectance spectroscopy based on Kubelka-Munk theoryKubelka-Munk theory is the basis quantitative theory of the near-infrared diffuse reflectance spectroscopy,the particle size of sample anbected the light scattering which directly affected the results of constructing models.Therefore,the scatter coefficient s was calculated based on Kubelka-Munk theory to study the changes of the scatter coefficient s after the mathematical methods processing,meanwhile,building the rocessing trajectory of PLS model to study whether the mathematical methods could eliminate the particle size for spectra from the view of scatter coefficient s.(1)Pretreatment methods for the impact of the scatter coefficient,comparing the pretreatment methods,such as multiplicative mcatter correction,standard normal variate,extended multiplicative scatter correction and savitzky-golay smoothing filters,was to study the correction for the scatter coefficient.The results showed that the scatter coefficients were similar after the pretreatment method raw spectra and SG9,meanwhile,the RPD values of raw spectra and SG9 models were also similar,it also showed that the change of the scattering coefficients s was directly related to the modeling results.And after MSC,SNV and EMSC,the scatter coefficients were changed larger than the raw spectra,and through the MSC,SNV and EMSC,the RPD values had greatly improved,which also indicated that pretreatment methods could eliminate the effect of particle size,and improve the modeling results.(2)Variable selection methods for the impact of the scatter coefficient,selected the variable importance in the projection as variable selection method,the results showed that,the RPD value of Codonopsis Radix was significantly increased after the VIP variable selction,however,the RPD value of Radix Scrophulariae was decreased after the VIP variable selction.At the same time,comparison of the scatter coefficint of non variable selection and variable selection of Codonopsis Radix and Radix Scrophulariae,we found that the scattering coefficient of Codonopsis Radix has decreased after VIP variable selection,but the scattering coefficient of Radix Scrophulariae has increased after VIP variable selection.All the above results showed that the change of the scatter coefficient directly affected the RPD values of modeling results,but the specific relationship between the two needed further studied. |
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