| Metal organic framework(MOFs),a kind of crystalline porous materials,has attracted more and more attention in the field of adsorption.Up to now,the research on the adsorption of MOFs materials is mainly focused on the separation of gases,the extraction of heavy metals,the explanation of pollutants in water and the adsorption of dyes.However,there are few applications in the adsorption and separation of active substances in plants by using MOFs materials as adsorbents.However,The extraction and separation methods of Galuteolin and Luteolin in plants are limited,and there are some disadvantages,such as tedious operation,time-consuming and high consumption of organic solvents and so on.The near infrared spectrum analyzer has the advantages of non-destructive,high efficiency and easy to realize on-line detection,and can be used for the content analysis of sample components.Therefore,the combination of adsorption technology and NIR for active components detection and mechanism research has attracted extensive attention of scholars.Based on this,this paper takes the active substances in Chrysanthemum as the test and analysis object,which mainly includes the following contents:(1)In order to enrich the active components,SiO2@ZIF-8 and SiO2@ZIF-67 adsorbents were synthesized by post-modification method,and their structures were characterized by FT-IR,SEM,TGA and XPS.The results showed that the adsorbents of MOFs composites were prepared successfully.(2)In order to explore the adsorption effect of adsorbent on the active components,the effects of the mass of the adsorbent,the shaking time and p H value of the solution on the adsorption effect were investigated.The results showed that the adsorption rate of Galuteolin could reach 92%when the mass of SiO2@ZIF-8 adsorbent was 0.2g and the p H value was 7 after shaking 20 minutes.The adsorption rate of luteolin can reach more than 95%when the mass of SiO2@ZIF-67 adsorbent is 0.25g and the p H value was 7 after oscillating 25 minutes.In summary,the results show that the application of MOFs composites to the enrichment of active components in plants shows a good enrichment effect.The adsorption mechanism of MOFs composite was analyzed.The results show that SiO2@ZIF-8 adsorbent belongs to Freundlich bilayer adsorption,which accords with quasi-second-order kinetic equation,and contains two binding sites of Zn metal center and N element.SiO2@ZIF-67 adsorbent belongs to the Langmuir monolayer adsorption,which conforms to the pseudo-second-order kinetic equation,The N site plays a significant in the adsorption effect.(3)The enriched adsorbents were applied to miniature near-infrared spectrometer and near-infrared spectrometer,respectively.The results of the miniature near-infrared spectrometer showed that after CARS variable screening and CWT spectral pretreatment,the correlation coefficient of the calibration model reached the best 0.9700.The accurate determination of trace Galuteolin in Chrysanthemum can be achieved by miniature near infrared spectroscopy.It provides a reference basis for the use and popularization of portable near infrared spectrometers.The results of near-infrared spectroscopy show that the wavelet transform(CWT)model of luteolin after enrichment is the best,and the correlation coefficient of the calibration model of luteolin sample after enrichment is 0.9334,which further shows that near-infrared spectroscopy can accurately determine luteolin and provide data reference for the combination of plant active substances enrichment and near-infrared spectroscopy.(4)In order to achieve accurate determination of Chrysanthemum components,Establishment of a new method for rapid determination of total amino acids and total polyphenols in Chrysanthemum by near-infrared diffuse reflectance spectroscopy.Take 10Chrysanthemum from different origins as test objects,Identification of Amino Acids and Polyphenols in Chrysanthemum by Ninhydrin Chromogenic Method and Folin Phenol Reagent Method.The partial least squares(PLS)method was used to establish a determination model of total amino acids and total polyphenols in Chrysanthemum,and finally the results of the quantitative model were analyzed and verified.In summary,we simply and efficiently synthesized a series of stable MOFs composites,which showed excellent adsorption properties for active substances in Chrysanthemum.Various research methods were used to explore the adsorption mechanism and application fields.In addition,in order to realize the accurate determination of Chrysanthemum,a new method for the determination of total amino acids and total polyphenols in Chrysanthemum from different origins areas was developed based on near-infrared diffuse reflectance technology.This paper broadens the field of adsorption of active substances by MOFs composites and the application prospect of near-infrared spectroscopy. |
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