| In this paper,four kinds of electrochemical detection methods of tyramine and tryptamine were developed and successfully applied in the food samples.The main contents were as follows:?1?In order to establish an electrochemical method on detecting tyramine.o-Aminophenol?OAP?was electropolymerized on the surface of glassy carbon electrode?GCE?to form the poly?o-aminophenol??POAP?film by cyclic voltammetry?CV?.Then the overoxidized poly?o-aminophenol?film modified GCE?OPOAP/GCE?was obtained by electrochemical treatment of POAP film in the alkaline solution.The modification method of GCE and detection conditions of tyramine were optimized.Electrochemical impedance spectroscopy?EIS?and scanning electron microscopy?SEM?were used to characterize the preparation process of OPOAP/GCE and binding ability of tyramine onto the OPOAP film.Furthermore,electrochemical properties of OPOAP/GCE was investigated by square wave voltammetry?SWV?.Finally,SWV was used to detect tyramine in rice vinegar.The results showed that OPOAP/GCE was fabricated via cyclic voltammetry in 0.3 mol/L perchloric acid solution with 0.01mol/L OAP and overoxidized in 0.09 mol/L Na OH solution,showed good electrochemical response on tyramine.The oxidation current and the concentration of tyramine had good linear relationship in the ranges of 1.0×10-71.0×10-5 mol/L and1.0×10-52.0×10-4mol/L,respectively.Based on the signal to noise ratio of 3,the detection limit was 5.4×10-8 mol/L.The OPOAP/GCE was applied to determine tyramine in rice vinegar,and the results were in good agreement with those obtained by HPLC.The fabrication of the modified electrode was simple,inexpensive,rapid,and suitable to detect tyramine in rice vinegar sample.?2?Pyrrole?Py?monomer was electropolymerized via amperometric i-t curve?i-t?method at a constant potential on the surface of GCE to form the poly?pyrrole??PPy?film.Then the overoxidized poly?pyrrole?film modified GCE?OPPy/GCE?was obtained by electrochemical treatment of PPy film in the alkaline solution.The modification method of GCE and detection conditions of tyramine were optimized.EIS,CV and SEM were used to characterize the preparation process of OPPy/GCE.Furthermore,electrochemical properties of OPPy/GCE was investigated by SWV.Finally,SWV was used to detecttyramine in wine.The results showed that OPPy/GCE was fabricated for 300 s at a potential of 0.7V via i-t in 0.1 mol/L nitric acid solution with phosphate buffer solution?p H7.0?and0.01mol/L Py,then overoxidized in 0.2mol/L Na OH solution,showed good electrochemical response on tyramine.The oxidation current and the concentration of tyramine had good linear relationship in the ranges of 8.0×10-83.0×10-6mol/L and 3.0×10-61.5×10-4mol/L,respectively.Based on the signal to noise ratio of 3,the detection limit was 1.6×10-8 mol/L.The OPPy/GCE was applied to determine tyramine in two kinds of wine,and the results were in good agreement with those obtained by HPLC.The preparation of the proposed modified electrode was simple,inexpensive,high sensitivity,good stability and used for the determination of tyramine in wine samples.?3?A sensitive modified electrode?Au CS/Clay/GCE?to tryptamine was fabricated by adding Au CS/Clay compounds on the surface of GCE.The methods and conditions of Au CS/Clay/GCE for tryptamine detection were optimized.SEM were used to characterize the preparation process of Au CS/Clay/GCE.Then,electrochemical properties of Au CS/Clay/GCE was investigated by SWV and i-t.I-t was used to determine tryptamine.The results showed that,the respond current had a good linear relationship with the concentration of tryptamine in 4.2×10-81.4×10-5 mol/L.Based on the signal to noise ratio of 3,the detection limit was 1.8×10-8mol/L.Furthermore,screen-printed electrode?PK-SPE?was used to detect tryptamine by SWV.The results showed that the oxidation current on PK-SPE and the concentration of tryptamine had good linear relationship in1.0×10-75.0×10-5mol/L.Finally,the tryptamine in ice vinegar and other samples were detected,and HPLC was used to verify.The preparation of Au CS/Clay/GCE was simple and high sensitivity,but it takes more time than PK-SPE for the detection of tryptamine.Small amount of samples?50 ?L?was uesd in testing on PK-SPE and showed that the detection technique was rapid and good selectivity.Both of the two proposed methods were suitable for the determination of tryptamine in samples of rice vinegar and other food samples. |
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