Investigation On Fluorescence And Electrochemical Integrated Dual-Signal Sensor For The Rapid Detection Of Iron Ions In Water

In recent years,eutrophication of lakes,rivers and other water bodies has emerged in endlessly,affecting water quality and harming the health of organisms.Nitrogen（N）and phosphorus（P）were considered to be the main control factors of water eutrophication.With the introduction of the theory of"iron limitation",the relationship between trace elements iron and algae proliferation has also become a hot topic in water bloom research.Iron will directly affect the absorption and utilization of other nutrients by algae by participating in various metabolic activities,and was considered to be the key factor limiting the growth of phytoplankton.Therefore,the detection of iron ions in water has gradually attracted people’s attention.At present,fluorescence spectrometry and electrochemical analysis have become important methods for iron ion detection and analysis because they can achieve visual detection and on-site analysis.Based on this,this paper studied and prepared fluorescent materials with high selectivity for iron ions,and constructed a fast response fluorescence/electrochemical dual-signal sensor for iron ions.Combining fluorescent visual rapid detection with electrochemical on-site accurate detection improves the sensitivity and linear range of iron ion detection,providing a new method for the detection of iron ions in complex environmental waters.The main contents are focused on the follows:1.A novel type of fluorescent and electrochemical dual-signal sensor was constructed for the sensitive and selective detection of iron ions(Fe³⁺)based on a fluorescent material（Chi-FITC-4MU）,which was synthesized by combining the organic dye4-methylumbelliferone（4-MU）,chitosan,and fluorescein isothiocyanate（FITC）in a simple step process.The 4-MU could bind to Fe³⁺to form a complex,and clearly improved the selectivity of Chi-FITC-4MU for Fe³⁺detection.FITC showed excellent fluorescence performance and chitosan was beneficial to the curing of the material.By solidifying the fluorescent material on an ITO surface,the dual-signal detection of Fe³⁺could be realized.Based on the unique fluorescence properties of this sensor,the concentration of Fe³⁺could be visualized in the linear range of 1×10^-7-1×10^-1M based on the degree of fluorescence quenching.Moreover,the highly sensitive and rapid analysis of low concentrations of Fe³⁺was achieved through the electrochemical properties of the ITO sensor.The limit of detection（LOD）and the corresponding linear range were 0.0184 n M and 0.1-500 n M,respectively.Furthermore,this dual-signal sensor was effectively used for the detection of Fe³⁺in actual water.2.In this work,an ion-imprinted fluorescent polymer(Fe³⁺-IIP)was prepared by a simple one-step sol-gel method using iron ion as the template ion and FITC as the fluorescence signal.Combining the high selectivity of ion imprinting technology,the visual sensitivity of fluorescence detection and electrochemical detection,the fluorescence and electrochemical dual-signal iron ion imprinting polymer sensor(Fe³⁺-IIP/ITO)was prepared.With the unique fluorescence characteristics of the sensor,the concentration of Fe³⁺can be visually detected according to the degree of fluorescence quenching within the range of 1×10^-9-1×10^-1M concentration,and the detection limit of fluorescence spectrum was 9.12 p M.Based on the electrochemical characteristics of the ITO sensor,a highly sensitive and rapid analysis of low concentration Fe³⁺was realized,with LOD of 0.775 p M and a linear range of0.001-200 n M.In addition,the effect of iron ion content on the growth of microcystis was preliminarily studied.The results will serve as the basis to provide data support for future water bloom early warning and control.