Study On Electrochemical Analysis Of Semicarbazide And Its Premetabolic Drugs

Nitrofurazone(NFZ)is often used as an antibiotic to prevent and treat diseases in fish and poultry.Azodicarbonamide(ADC)is used as a dough improver in the food industry.Their metabolite,semicarbazide(SEM),may be genotoxic and carcinogenic to animals.Developing a rapid and simple detection method to prevent the harm of three drugs to human is a work of practical significance.In This paper,several favorable attempts have been made to complete this task by using electrochemical techniques.The main research contents are as follows:1.Based on the high solubility of ADC in hot solution and its electrostatic interaction with Nation film,a new electroanalytical method was developed for the determination of ADC by using Nafion film electrode.The effect of temperature on the solubility of ADC and the mechanism of the reduction reaction of ADC on Nafion film electrode were investigated.Under the experimental conditions such as water bath at a constant temperature of 80?,pH 6.0 and optimal test parameters,the differential pulse voltammetric response was proportional to the concentration of ADC in the range of0.93~10.5 ?g/L,and the detection limit was estimated to 0.58 ?g/L.The relative standard deviation was less than 5.86% and the recovery was 95.8%~104.0% for the determination of the ADC in flour samples.SEM and NFZ did not interfere with the determination of ADC.2.Mixing 5-amino-2-mercapto-1,3,4-thiadiazole(p-AMT)and graphene oxide(GOx)as raw materials,the conductive copolymer modified electrode(p-AMT+GOx/GCE)was prepared by using electrochemical copolymerization on the surface of glassy carbon electrode(GCE).Based on the selective response of p-AMT+GOx/GCE to NFZ at negative potential,the electrochemical analysis of NFZ has been developed indrugs and disinfectants.Under the optimal experimental conditions,the differential pulse current of the conductive copolymer modified electrode showed a linear relationship with concentration of NFZ in the range of 0.02~2.00 ?g/mL with a linear correlation coefficient of 0.997 and a detection limit of 0.01 ?g/mL.The relative standard deviations(RSD)were less than 5.56(n=5)and the spiked recoveries ranged from 95.2% to 104% for the determination of the actual samples.3.The modified electrode GOx/GCE was prepared by coating GOx on the surface of GCE,and then the conductive polymer modified electrode p-DMcT/GOx/GCE was prepared by electropoly merization of 2,5-dimercapto-1,3,4-thiadiazole(p-DMcT)on the surface of GOx/GCE.The characteristics of the modified electrode were characterized by electrochemical impedance spectroscopy and cyclic voltammetry.An electrochemical mothed for detecting SEM has been developed by utilizing selective response of p-DMcT/GOx/GCE to SEM at positive potential.After optimizing the pH of the electrolyte,enrichment time and electrochemical parameters,the differential pulse current of p-DMcT/GOx/GCE showed a linear relationship with concentration of SEM in the range of 0.1~45 ?g/mL with a linear correlation coefficient of 0.992 and a detection limit of 0.087 ?g/mL.The relative standard deviations(RSD)were less than4.15(n=5)and the spiked recoveries ranged from 92.5% ~ 106% for the determination of the actual samples.4.The modified electrode CNTs/GCE was prepared by coating carbon nanotubes(CNTs)on the surface of GCE,and then the conductive polymer modified electrode p-DMcT/CNTs/GCE was prepared by electropolymerizing p-DMcT on CNTs/GCE surface.The selective response of p-DMcT/CNTs/GCE at potential 0.20 V and 0.60 V to NFZ and SEM respectively was used to determine simultaneously NFZ and SEM.After optimizing the experimental conditions,the differential pulse current of p-DMcT/CNTs/GCE is linearly related to the concentration of NFZ in the range of0.01~2.0 ?g/mL and the concentration of SEM in the range of 0.1~24 ?g/mL,respectively.The linear correlation coefficients are 0.997 and 0.996,and the detection limits are 0.0078 ?g/mL and 0.09 ?g/mL.The relative standard deviations(RSD)for actual samples were less than 4.37(n=5)and 4.25(n=5),respectively.The recoveries were 94%~108.6% and 97.6%~106% respectively.