Design And Application Of Luteolin Modified Acidity Electrode Set

On-line or in-vivo measurements of many food production processes and human pathological indicators,it is necessary to monitor the acidity of these samples.Most of the acidity is in the range of p H 2.00～12.00,and some production processes require higher acidity.Therefore,a safe and non-toxic acidity detecting device is required.In this paper,an electrochemical sensor with the characteristics of biochemical safety,wide-range,high-acidity,all-solid-state has been developed.Luteolin,a traditional Chinese medicine active ingredient,is used as an acidity selective reagent to prepare electrodes with conventional and micron size.These electrodes are expected to use for the monitoring of acidity parameters in the production process and the detection of acidity of micro-body liquid.This paper mainly carries out the following researches:（1）A luteolin carbon paste electrode is prepared by mixing luteolin,graphite powder and solid paraffin at a mass ratio of 1:3:1,and further is combined with a self-made conductive gel type all-solid Ag/Ag Cl reference electrode and a platinum wire electrode together to form a luteolin carbon paste electrode set.The electrochemical responses of the electrode set to p H 2.00～10.00 PBS and 1.00～10.0 mol/L H₂SO₄solution are studied by cyclic voltammetry.The results show that there is a linear relationship between the oxidation peak potentials(E_pa)and the acidity of the solution.The linear regression equations are E_pa（V）=-0.0600 p H+0.715（r=0.998）and E_pa（V）=0.0145c（H₂SO₄）+0.744（r=0.999）.Similar linear responses to HCl and HCl O₄solution in the range of H⁺concentration from 1.00 to 10.0mol/L have been found.Common ions do not interfere with above-mentioned determinations.The method is applied to the monitoring of acidity in syrup production process,acidity of human urine and serum,or the concentration of strong acid in industrial production.The measurement results are satisfactory.（2）A luteolin carbon fiber microelectrode is prepared by smearing a paste mixed by luteolin,graphite powder and solid paraffin at a mass ratio of 1:3:1 on the surface of the carbon fiber,and further is combined with a miniature self-made conductive gel type all-solid Ag/Ag Cl reference electrode and a micro platinum wire electrode together to make up a luteolin carbon fiber microelectrode set.The electrochemical behaviors of the microelectrode set in PBS of p H 2.00～10.00 are studied by square wave voltammetry.The results show that the oxidation peak potentials have a good linear response to the acidity of the solution,and the linear regression equation is E_pa（V）=-0.0567p H+0.603（r=0.999）.The sensor has the advantages of simple manufacturing method,high sensitivity,strong anti-interference ability,non-toxicity and miniaturization.It is applied to the determination of human sweat and saliva acidity with satisfactory results.This study has laid the foundation for the development of new medical detection devices.