Study Of Hesperidin,glucose And Fructose On Electrochemical Analysis

Due to the portable equipment,fast analysis speed,and high detection sensitivity,electrochemical sensors are more and more favored by pharmaceutical workers in the fast inspection and quality evaluation of traditional Chinese medicine（TCM）.Hesperidin（HES）is an important active component in tangerine peel and other TCM.High performance liquid chromatography is mostly used in its detection.There are also reports on electrochemical sensors for the detection of HES,but the selectivity to HES of these sensors is relatively poor according to the mechanism of electrochemical sensor;glucose and fructose are commonly found in honey,Codonopsis pilosula and other TCM.Liquid chromatography and thin layer chromatography are the mostly detection methods.Spectral analysis methods such as infrared spectroscopy and nuclear magnetic resonance spectroscopy also used for the fast qualitative analysis of glucose and fructose.There are also studies on electrochemical sensors,but none can simultaneously analyse glucose and fructose.The characteristics of molecularly imprinted polymer（MIP）and conductive polymer can give the sensor a certain selectivity.In order to realize the selective and sensitive determination of HES and simultaneous qualitative and quantitative analysis of glucose and fructose,this paper constructed a molecular imprinting electrochemical sensor based on ultrafine activated carbon（UAC）for the highly sensitive selection of HES in tangerine peel;an electrochemical sensor based on the aniline-guanine copolymer-AuNPs complex（PAG-AuNPs）was constructed for the simultaneous determination of glucose and fructose.The specific content is as follows:1.Highly sensitive and selective quantitative detection of hesperidin based on UAC molecular imprinting electrochemical sensorAs HES is a key indicator of some herbs and TCM preparations,it is important to realize its sensitive,fast and high selective detection.In this work,prepared UAC with high electrical conductivity was introduced as base decorated material of electrode,then the MIP was prepared by self-assembly method and electro-polymerization method sequentially on the electrode by using HES as template molecular and o-aminothiophenol as functional monomer.Scanning electron microscope（SEM）,cyclic voltammetry（CV）and electrochemical impedance spectroscopy（EIS）were employed to characterize the morphological features and the stepwise modification of electrode,separately.The influence of p H,ratio of monomer to template,self-assembly time and so on were investigated and optimized.Under the optimized condition,the fabricated sensor exhibits a wide linear range from 85 n M to30μM with a low detection limit of 45 n M（S/N=3）.The constructed sensor has good repeatability and reproducibility,and the RSD is less than 2.18%.After being placed at room temperature for 10 days,its performance is still maintained 97.84%of the initial’s.The standard addition method was used to analyze the tangerine peel extract,and the recovery rate of addition was in the range of 99.00%～104.40%,indicating that the constructed sensor can be used for the highly selective and sensitive detection of HES in real samples.2.Simultaneous qualitative and quantitative detection of glucose and fructose by electrochemical sensor based on PAG-AuNPsIt has extremely important practical significance to realize the selective quantitative detection of glucose and fructose in TCM that directly or indirectly use glucose and fructose as quality markers.And as a pair of isomers with very similar structures,glucose and fructose also have the characteristics of mutarotation and ring formation which bring great challenges to achieve their simultaneously selective and quantitative detection.In this work,PAG-AuNPs was prepared by a facile one-step synthesis method in H₂SO₄,which using HAu Cl₄ as the oxidant,aniline and guanine as the reducant.Through"doping and dedoping"characteristics of polyaniline（PANI）and the unequal nucleophilic reaction between guanine and glucose/fructose,it innovatively realized the selective quantitative detection of glucose and fructose on the electrochemical sensor innovatively without relying on the help of biological enzymes,molecular imprinting polymer and boric acid functionalized material.The morphology,chemical structure and electrochemical properties of PAG-AuNPs were characterized by SEM,Fourier transform infrared spectroscopy,Raman spectroscopy,CV and EIS;the affinity of PAG-AuNPs to glucose and fructose was compared by combining the ultraviolet-visible spectrum with the scatchard equation;the different reactions between PAG-AuNPs and glucose/fructose were characterized by the EIS.The modification amount of PAG-AuNPs and the testing environment and other conditions have been optimized.Under optimized conditions,the constructed sensor has a certain selective and quantitative detection ability for glucose and fructose.The constructed electrode has good reproducibility,selectivity,stability and certain practical applicability.In summary,this paper constructs a molecularly imprinted electrochemical sensor based on UAC,which realizes the selective and quantitative detection of hesperidin in complex systems such as TCM.The constructed sensor has better selectivity for hesperidin than other reported electrochemical sensors;an electrochemical sensor decorated with PAG-AuNPs was constructed,which realizes the qualitive and quantitative detection of glucose and fructose simultaneously for the first time based on electrochemical sensor.