Disposable Electrode Based On Electrochemical Detection Of Peroxide In Food

Peroxide is a kind of compound containing peroxygen bond,which can be decomposed by ultraviolet light or interact with transition metal to generate free radicals.When it was ingested by human body,it can cause a series of oxidative damage,which is harmful to human health.There are two main sources of peroxide in food:one is hydrogen peroxide that is artificially added as a bleaching agent and a bactericide,the other is the peroxide produced by oxidation of oil.Therefore,it is significant to establish a rapid method for detecting peroxides in foods.Electrochemistry is a fast,sensitive,and accurate method for the trace analysis of analyte.The electrode performance can be improved by modifying the electrode to meet different needs in detection.The iodometric method is used to detect the peroxide concentration indirectly by detecting the concentration of iodide ions after reacting with peroxide.The protonation of chitosan under acidic conditions could be used to adsorb iodide ions.In this study,chitosan was used as binder and adsorbent.Graphite powder was used as conductive material to prepare paper-based electrode.Peroxidation was detected by detecting the concentration of iodide ion.The main findings were as following:1.Preparation and electrochemical behaviors of chitosan graphite glass-carbon electrode(CTS-G-GCE)The conductive paste was dripped on the surface of glassy carbon electrode and dried to obtain chitosan-graphite-glassy carbon electrode(CTS-G-GCE).Differential pulse voltammetry was used to study the effect of chitosan on the response of the electrode to iodine ion.Under the enrichment condition of 0.6 V 180 s,the response of CTS-G-GCE to iodide ion was 3.14 times of bare electrode,indicating that chitosan could significantly increase the response of iodide ion.Cyclic voltammetry was used to study the electrochemical process of iodide ion on the electrode surface.The redox peak potential distance was between 100 and 200 mV,indicating that the iodide ion underwent a quasi-reversible redox reaction on the surface of the electrode.The oxidation peak currents of iodide ion were also studied at different scanning speeds.The oxidation peak current value was linearly related to the scanning speed,indicating that the electrochemical process of iodide ion on the electrode surface was adsorption control.2.Determination of peroxide by CTS-G-GCE The acidic buffer solution system was the main component of the electrolysis support solution,and n-propanol was the oil-soluble substance and water-soluble substances in the detection solution to make the peroxide react fully with potassium iodide.The optimized detection conditions were acetic acid-sodium acetate buffer solution with pH 5.0 as the main component of the detection solution,added with 20%n-propanol,and enriched for 210 s at 0.6 V.The CTS-G-GCE had an obvious logarithmic response to potassium iodide and lauroyl peroxide.The correlation coefficients were R~2=0.993 and R~2=0.986,respectively.It proved that the modified material could be used for peroxide detection.3.Preparation,Characterization and Detection method of Chitosan-Graphite-Paper Electrode(CTS-G-PE)The electrode slurry was written on a filter paper and dried at room temperature,and then wax-sealed to obtain a paper electrode(CTS-G-PE).The CV of the paper electrode in the electrolytic support solution and the electrolytic support solution containing potassium iodide was analyzed,and it was found that the electrolytic support liquid did not interfere with the detection,and the potassium iodide had an irreversible redox reaction on the electrode surface.The optimum detection conditions of CTS-G-PE were pH6.0,enrichment potential of 0.9 V,and enrichment time of 300 s.Under the optimal conditions,the peroxide value and hydrogen peroxide logarithmic detection range were1.85~39.30 mmol/kg and 0.075~1.5 mg/kg,and the correlation coefficients were R~2=0.998and R~2=0.999,respectively.4.Detection performance evaluation and sample detection The reproducibility,accuracy,anti-interference and batch-to-batch difference of the detection method were evaluated.The reproducibility(n=3)was good,and the peroxide value test results were consistent with the national standard test results(p>0.05).Common anions and homologous halogen elements had no significant effect on the detection of iodide ions,and the anti-interference was good.The results of the two batches of electrodes(20 per batch)were consistent(p>0.05).The recovery rate of hydrogen peroxide addition standard recovery was 90~103%.The results showed that the paper electrode detected the peroxide in the food accurately and reliably.In this study,a disposable paper electrode was simply prepared under room temperature to detect the peroxide value rapidly in food.It developed CTS-G-PE in an easy way,providing a certain theoretical and technical basis for electrochemical detection of peroxides in foods.