Preparation Of CNTs-COOH Chemically Modified Electrode And Its Application In MG Detection

Malachite green（MG）is used in the treatment of fish diseases,which has high residue,persistence and is not easy to degrade,threatening human health.This article summarizes the research status of MG,the application of chemically modified electrodes and carbon nanotubes.Developement of a sensitive electrochemical sensor based on carboxylated carbon nanotubes modified glassy carbonelectrode（CNTs-COOH/GCE）,carboxylatedcarbon nanotubes/ethylenediamine modified carbon paste electrode（CNTs-COOH/En/CPE）and carboxylated carbon nanotubes modified gold electrode（CNTs-COOH/Au）to MG.Carboxylated carbon nanotubes（CNTs-COOH）were used to modify glassy carbon electrode（GCE）（CNTs-COOH/GCE）for construting electrochemical sensor to detecte MG.The morphology of CNTs-COOH was characterized by SEM,and it has a slender tubular structure.The modification amount of CNTs-COOH,the type of buffer system,the enrichment time of MG and p H value were optimized by cyclic voltammetry（CV）.The CV was tested at different scanning speeds to explore the oxidation process of MG within the potential range of 0.2-1.0 V,which happened two irreversible oxidation reactions.The CV calculated the area of modified electrode and Chronocoulometry studed the saturated adsorption capacity of MG.This indicates that the special tubular structure of CNTs-COOH increases the area of GCE and can adsorb more MG.The square wave voltammetry（SWV）was used to detect MG solution on CNTs-COOH/GCE.The linear range is 8.0×10^-8～4.0×10^-6mol/L.The detection limit was 1.62×10^-8mol/L（S/N=3）.The interference experiment and sample recovery experiment were carried out on the CNTs-COOH/GCE,and the average recovery is 101.2%.An electrochemical sensor based on CNTs-COOH/En/CPE was constructed to detect MG.5:1 preparation of carbon paste electrode（CPE）with graphite and solid paraffin wax.CNTs-COOH/En/CPE was prepared on CPE modified by CNTs-COOH through the crosslinking of En.The standing time of En and the amount of CNTs-COOH were optimized by CV.The CV calculated the area of modified electrode and Chronocoulometry studed the saturated adsorption capacity of MG.The results showed that CNTs-COOH increased the area of CPE,and the addition of En was beneficial to adsorb more MG.The SWV was used to study CNTs-COOH/En/GPE for quantitative detection of MG solution,and the linear range is 8.0×10^-9～1.0×10^-7mol/L.The detection limit is 2.83×10^-9mol/L（S/N=3）.The interference experiment and sample recovery experiment were carried out on the CNTs-COOH/En/GPE,and the average recovery is 101.7%.Carboxylated carbon nanotubes（CNTs-COOH）were used to modify gold electrode（Au）（CNTs-COOH/Au）for construting electrochemical sensor to detecte MG.The modified amount of CNTs-COOH was optimized.The CV calculated the area of modified electrode and Chronocoulometry studed the saturated adsorption capacity of MG.The results showed that CNTs-COOH increased the area of GCE and adsorbed more MG.The SWV method was used to study CNTs-COOH/Au for quantitative detection of MG solution,and the linear range is 5.0×10^-8～2.0×10^-6mol/L.The detection range is 9.3×10^-9mol/L（S/N=3）.At the same time,the interference experiment and sample recovery experiment were carried out on the modified electrode,and the average recovery is 101.3%.