New Electrochemical Methods For Detecting Weak Base And Amino Acid Based On Proton-coupled Electron Transfer Reaction

Proton coupling electron transfer reaction(PCET)is an important class of reactions universally existing in the chemical and biological fields.Hydroquinone and p-benzoquinone have been extensively studied as typical PCET reactions.In the unbuffered and aprotic solutions,the voltammetric behavior of hydroquinone and p-benzoquinone becomes complicated and difficult to interpret.Our team has studied the voltammetric behavior of hydroquinone and p-benzoquinone in a dilute buffer solution and found that intense pH changes at the electrode surface can form new voltammograms.During the oxidation of hydroquinone,electrons are losted and protons are released.The base acts as a proton acceptor and can accept protons,inhibiting pH changes at the electrode surface and affecting its voltammetric behavior.During the reduction of p-benzoquinone,electrons are obtained and protons are accepted.The acid acts as a proton donor and can provide protons,inhibiting the pH change at the electrode surface and then controling the voltammetric behavior of p-benzoquinone.Amino acids,amphipathic substances,have effect on the voltammetric behavior of hydroquinone and p-benzoquinone.By studying the effects of acids,bases and amino acids on the voltammetric behavior of hydroquinone and p-benzoquinone,we established an electrochemical method for the determination of bases and amino acids.In this paper,we studied the effect of the proton acceptors(sodium bicarbonate)on the oxidation of hydroquinone in aqueous solution using the redox reaction of p-xyloquinone and hydroquinone.The effects of proton acceptors and donors(proline)on the redox process of hydroquinone and p-xyloquinone in non-aqueous solvents.The peak current height of the new peak has a good linear relationship with the concentration of the proton acceptors or the proton donors and independent on the concentration of p-xyloquinone and hydroquinone.We establish a differential pulse voltammetric method to measure the contents of the sodium bicarbonate in different weak alkali mineral water and The proline content in the proline water model.This method is relatively simple,high in sensitivity and strong in anti-interference,and not requiring complicated sample pre-treatment.