Study On The Detection Of Quercetin By Electrochemical Sensor Based On Glassy Carbon Electrode

Quercetin（Qu）is one of the most abundant flavonoids in human diet.An appropriate amount of Quercetin can help to resist oxidation and eliminate free radicals in human body.However,high concentration of Quercetin is easy to cause adverse reactions and induce inflammation,joint pain and stiffness,so it is very important to detect Quercetin.At present,there are many methods to detect Qu in clinical applications,including fluorescence,spectrophotometry,capillary electrophoresis,and high performance liquid chromatography.The electrochemical sensor has the advantages of fast,sensitive,simple,and portable,so this paper studies the construction of an electrochemical sensor to detect Qu.In this study,Heme/GCE,Pyrole/CoNPs/GCE were prepared from cobalt nanoparticles（CoNPs）,antimony trioxide（Sb₂O₃）,multi-walled carbon nanotubes（MWCNTs）and active substances with diverse physiological activities and unique properties,heme,pyrrole and Sb₂O₃@MWCNTs/GCE quercetin sensor.The main research work is as follows:（1）Study on sensor Heme/GCE for quercetin detection:Heme was deposited on glassy carbon electrode（GCE）by i-t method,and the electrochemical sensor Heme/GCE was constructed.It was characterized by SEM and electrochemistry.Under the optimal conditions,quercetin was detected by cyclic voltammetry（CV）and differential pulse voltammetry（DPV）,and the relationship between quercetin and peak current with different concentrations was obtained.The peak potential was 0.3 V.In the CV method,the low concentration linear equation is:I=0.0747+0.2854 c,and the high concentration linear equation is:I=0.9039+0.0042 c,where c is the concentration of Qu,I is the current value,and the linear range is 0.1～12μM respectively15～700μM;R²is 0.99561 and 0.99008 respectively;Sensitivity is 0.12μA·μM^-1·cm^-2,detection limit is0.134μM.In the DPV method,the low concentration linear equation is:I=0.63712+0.22284 c,the high concentration linear equation is:I=3.79564+0.00597c,R²is0.99253 and 0.99257 respectively;Sensitivity is 0.09μA·μM^-1·cm^-2,detection limit is0.063μM.This chapter studies the anti-interference,stability and reproducibility of the sensor,which proves that the sensor has good anti-interference,stability and reproducibility.The recovery rate of quercetin in loquat leaf solution samples was determined by standard addition method using DPV.The results showed that the recovery rate of the sensor ranged from 98.55%to 102.89%,indicating that the sensor had good performance,and its RSD was lower than 3.70%,so the sensor could be used for the detection of actual samples.（2）Study on Pyrrole/CoNPs/GCE sensor for quercetin detection:CoNPs were deposited on GCE by i-t method,and active substance Pyrole was modified on the surface of CoNPs/GCE electrode.It was characterized by SEM and electrochemistry.Using the DPV method to detect Qu,the peak potential is about 0.3 V.At low concentration,the linear equation for fitting the effective peak current with the concentration is:I_P=0.63573 c-0.00254,and the linear range is 0.1～12μM,R²=0.99137;At high concentration,the linear equation is:I_P=0.06581c+5.84004,and the linear range is 16～100μM,R²=0.99485。Sensitivity is 8.98μA·μM^-1·cm^-2,detection limit is 0.033μM.This chapter studies the anti-interference,stability and reproducibility of the sensor,which proves that the sensor has good anti-interference,stability and reproducibility.The recovery rate of quercetin in Ginkgo biloba leaf samples was determined by standard addition method using DPV.The results showed that the recovery rate of the sensor ranged from 95.50%to 103.86%,indicating that the sensor had good performance,and its RSD was lower than 2.43%,so the sensor could be used for the detection of actual samples.（3）Sensor for quercetin detection Sb₂O₃@MWCNTs/GCE study:The mixture of Sb₂O₃and MWCNTs was deposited on GCE by i-t method Sb₂O₃@MWCNTs/GCE electrochemical sensor.Then conduct SEM and EIS characterization.Square-wave voltammetry（SWV）is used to detect Qu with different concentrations,and the peak potential is 0.3 V.The linear relationship between the concentration of Qu and the effective peak current is:I_P=0.765 c+1.742,and the linear range is 0.83～20.8μM.R²=0.995,sensitivity 10.82μA·μM^-1·cm^-2,detection limit is 0.276μM。This chapter studies the anti-interference,stability and reproducibility of the sensor,which proves that the sensor has good anti-interference,stability and reproducibility.The recovery rate of quercetin in Ginkgo biloba leaf samples was determined by standard addition method using SWV.The results showed that the recovery rate of the sensor ranged from 97.08%to 102.52%,indicating that the sensor had good performance and its RSD was lower than 5.29%,so the sensor could be used for the detection of actual samples.（4）For sensor Heme/GCE,the linear range is 0.1～700μM.Sensitivity is 0.09μA·μM^-1·cm^-2,detection limit is 0.063μM.The recovery rate used for actual sample detection is between 98.55%and 102.89%,and the RSD is lower than 3.70%.For sensor Pyrrole/CoNPs/GCE,the linear range is 0.1～100μM.Sensitivity is 8.98μA·μM^-1·cm^-2,detection limit is 0.033μM.The recovery rate used for actual sample detection is between 95.50%and 103.86%,and the RSD is less than 2.43%.For sensors Sb₂O₃@MWCNTs/GCE,linear range:0.83～20.8μM.Sensitivity is 10.82μA·μM^-1·cm^-2,detection limit is 0.276μM.The recovery rate used for the actual detection of samples is 97.08～102.52%,and the RSD is lower than 5.29%.The linear range of sensor Heme/GCE is the widest,the detection limit of sensor Pyrrole/CoNPs/GCE is the lowest,and the sensor Sb₂O₃@MWCNTs/GCE has the highest sensitivity.