Study Of The Preparation And Application Of The Capsaicin Electrochemical Sensor Based On The Carbon Materials

Capsaicin is the source of pungency,flavor and hotness in peppers.It is gaining widespread application in food pharmaceutical industries in recent years.However,there is still no definitive method to determinate the capsaicin concentration,further to evaluate the pepper spiciness.What`s more,the use of capsaicin in pharmaceutical field must to be qualified.Scoville Organoleptic Test is the most conventional method to measure the heat of chili peppers.While the accuracy of this method has been under controversy due to the subjectivity of volunteers,who may have different sensitivity to pungency.The instrument-assisted techniques like HPLC for capsaicin detection suffer from high cost and complicated processes.Therefore,a rapist detection method for capsaicin which was suitable for commercial development would be highly encouraged.In this work,some simple,low-cost,novel electrochemical capsaicin sensors were constructed based on carbon materials and screen printed electrode,which demonstrate the large applications in the future.(1)Graphene,with large specific surface area and good conductivity,has attracted enormous attention in electrochemical analysis field in recent years.In this paper,graphene was treated by PSS to make the surface negative charged,and then Ag/Ag2O-PSS-rGO hybrid was prepared by direct adsorption of the positively charged AgNPs on the surface of the negatively charged PSS-rGO.The prepared composite was characterized by Transmission Electron Microscopy(TEM)and X-ray Photoelectron Spectroscopy(XPS).Ag/Ag2O-PSS-rGO was modified on the SPE to construct capsaicin electrochemical sensor.The sensing properties of Ag/Ag2O-PSS-rGO/SPE were investigated.Under the optimal conditions,the linear range of capsaicin was found to be 1.0-60 ?mol·L-1 and the LOD was 0.40 ?mol·L-1(S/N = 3)by DPSV.The as prepared sensor has been also successfully applied in practical detection of capsaicin in chili peppers and the recoveries of three samples vary from 99.0% to 102.0%.(2)Graphite is one of carbon materials with high stability and low-cost properties.In this work,PSS and PDDA were used to functionalize graphite to prepare the PSS-Grp?PDDA-Grp.The prepared PSS-Grp and PDDA-Grp were modified on the SPE surface to prepare different charged electrodes.The electrochemical performances of modified electrodes were investigated by EIS and AsdSV.The PSS-Grp/SPE showed best electrochemical activity for capsaicin ascribed to the high conductivity of PSS-Grp and the mutual attraction between the negatively charged PSS-Grp and capsaicin.Under the optimized conditions,the as-prepared PSS-Grp/SPE also shows a wide linear range of 0.3-70 ?mol·L-1 and low detection limit of 0.10 ?mol·L-1.The obtained result implies a promising application of this low-cost and sensitive sensor for capsaicin determination in the future.(3)Amino-functionalized carbon microspheres(NH2-CMS)were prepared using glucose?3-aminopropyltrimethoxysilane(APTMS)and ammonium hydroxide through hydrothermal synthesis and ultrasonication.The prepared composite was modified on the SPE to construct the electrochemical capsaicin sensor.The modified electrode was characterized by SEM and cyclic voltammetry(CV).NH2-CMS effectively improve the conductivity,the electric catalytic activity and specific surface area of the bare SPE.The electrochemical sensing of capsaicin was investigated at NH2-CMS/SPE under the optimized conditions.Linear calibration curve in the range of 0.20-80 ?mol·L-1 was obtained for capsaicin with a detection limit of 0.067 ?mol·L-1(based on S/N = 3).