Electrochemical Sensors Based On Nitrogen-doped Carbon Nanotubes For Rapid Detection Of Bromate And Metformin In Aqueous Environment

With the rapid development of industrialization and economy,more and more emerging contaminants are discharged into the environment,causing great harm to the ecological environment and human health.Therefore,it is urgent to develop simple,portable,sensitive and fast detection new methods to meet the needs of emergency detection and on-site real-time monitoring of environmental emerging contaminants.Electrochemical sensors have attracted great attention in the field of rapid screening and detection of environmental toxic pollutants because of their advantages of low cost,fast detection speed,high sensitivity,simple operation and easy miniaturization.Based on this research background,aiming at the detection of toxic emerging contaminants in the environment,this paper constructs a high sensitive and specific rapid detection method based on electrochemical sensor,and takes nitrogen-doped carbon nanotubes as modified materials to improve the sensitivity,reduce the limit of detection and other key performance indicators of the sensor.This paper mainly includes the following contents:1.In order to meet the needs of high sensitive and rapid detection of bromate,a disinfection by-product of drinking water,an electrochemical hemoglobin sensor was constructed by using nitrogen-doped carbon nanotubes as the immobilized substrate of hemoglobin.Nitrogen-doped carbon nanotubes have large specific surface area and high conductivity,which can greatly promote the electron transfer rate and improve the conductivity and detection sensitivity of the sensor,so that the sensor shows excellent analytical and detection performance in the detection of bromate:low detection limit（75.4 nmol/L）,fast response speed（<5 s）and wide linear range(1×10^-7～4.66×10^-5mol/L),with good reproducibility（7.04%）.Good recoveries（91.8%～116.7%）were also obtained in the detection of reservoir water,river water,mineral water and tap water samples.The electrochemical hemoglobin sensor based on nitrogen-doped carbon nanotubes provides a new method for the rapid detection of bromate in environmental water samples.2.In the presence of Cu²⁺,the electrochemical sensor constructed with nitrogen-doped carbon nanotubes as electrode recognition element realizes the high sensitive and rapid detection of metformin.The highly conductive catalysis of nitrogen-doped carbon nanotubes,combined with the coordination catalytic effect of Cu²⁺on metformin,can achieve the effect of enrichment,increase the local concentration of metformin participating in the reaction on the electrode surface,catalyze its electrochemical oxidation,and significantly improve the detection performance of the sensor.The sensitivity of the sensor to metformin is 4.5921μA/（μmol/L）,the linear range is 0.3～10μmol/L,and the detection limit is as low as13.96 nmol/L.the highly sensitive and rapid detection of metformin in environmental water samples is successfully realized,and the recovery is 90.2%～108.8%.This study provides a convenient,efficient and cheap analytical method for the highly sensitive and rapid detection of metformin.