Detection Of Trace Environmental Hormones In Water Based On Molecularly Imprinted Electrochemical Sensing

Environmental hormone is an exogenous interfering substance released to the natural environment by human beings in production and living activities and existing in nature itself,which will affect the normal hormone secretion in human body or animal body.With the continuous development of industry,a large number of environmental hormones are released into the environment.Due to the special physical and chemical properties of environmental hormones,they have high environmental retention and can be enriched continuously through the food chain.Environmental hormones are harmful to all major human systems and have carcinogenic effects Therefore,it is of great significance to carry out research on environmental hormone detection methods.In this thesis,17?-estradiol,which has the highest endocrine activity among environmental hormones,is taken as the research object,and an electrochemical sensing detection platform based on molecular imprinting technology is established.The detection platform is designed from the aspects of liquid transmission pipeline,electrochemical detection cell structure and the realization of automatic sampling function of the platform.Electrochemical sensors,which are the core components of the platform,are prepared by electropolymerization and their preparation parameters are optimized.The sensing characteristics of electrochemical sensors for environmental hormones were studied by using the test platform test with optimized sensor performance.The feasibility and stability of the detection platform were verified by using actual food samples for standard addition and recovery.The main conclusions of this study are as follows1)Establish an electrochemical sensing detection platform.The hardware system is designed from liquid transmission pipeline,electrochemical detection cell and other parts.The electrochemical detection cell can reasonably place three electrodes of cyclic voltammetry,and adopt pressure sealing and thread sealing tape sealing to ensure that the detection cell has good sealing performance and the accuracy of detection results is higher.A liquid transmission pipeline is designed according to the detection work flow,and the pipeline comprises a detection branch and a drying branch.In the software part,LabVIEW software is used as the development platform,and the human-computer interaction control interface of the detection system is written.The main functions of the software include system parameter setting,key control and liquid transmission pipeline control.2)The sensitive element 17?-estradiol molecularly imprinted polymer in the electrochemical sensor is prepared by an electropolymerization method,and the carrier electrode of the sensitive element is modified by a nano porous gold film to improve the performance of the electrochemical sensor.Taking the response of electrochemical sensor to standard concentration of 17?-estradiol as evaluation index,the preparation conditions such as acetonitrile as solvent,1:10 ratio of template molecule to functional monomer,and 75 scanning cycles were optimized.After optimization,the response of the sensor to the standard concentration of 17?-estradiol increased from 0.09?A to 0.913?A.Through the completion of the platform detection duration optimization test,the optimal adsorption duration of the sensor is 35 minutes and the optimal elution duration is 30 minutes.Cyclic voltammetry,electrochemical impedance spectroscopy,scanning electron microscope and energy spectrum were used to characterize the sensor.The results showed that the electrochemical behavior,surface morphology and surface element content of the sensor were consistent with theoretical analysis.3)Use the detection platform to detect the sensor performance.The sensor response value has a positive correlation with the logarithm of 17?-estradiol concentration in the range of 1×10-12 to 1×10-5mol/L.When the signal-to-noise ratio is 3,the detection limit of the sensor is about 1×10-13mol/L.The selection factors of molecularly imprinted sensors for nonylphenol,ethinylestradiol and bisphenol A are 8.7,14 and 7.0 respectively.Compared with non-molecularly imprinted sensors,the relative selection factors of molecularly imprinted sensors are 5.1,8.4 and 9.6 respectively.The selection factors and relative selection factors of molecularly imprinted sensors are much larger than 1.In the repeatability and reusability tests,the repeatability evaluation indexes R of sensors are 98.86%,98.59%and 99.01%respectively.The sensor remained at 89.81%and 81.54%response values in the second and third weeks.The above results show that electrochemical sensors have good sensitivity,selectivity,stability and reusability.In the actual detection of food samples by the standard addition and recovery method,the standard addition and recovery rates of the three samples are all between 95.1%and 106.0%,and the relative standard deviation is less than 6.09%.The electrochemical sensing detection platform based on molecular imprinting technology developed in this paper has high feasibility in the detection of 17?-estradiol in food samples.It can provide reference and technical support for subsequent environmental hormone detection.