Synthesis And Evaluation Of Fluorescent Probe For Sulfur Dioxide Derivatives

Sulfur dioxide（SO₂）,as one of the environment pollutants,could cause serious harm to the ecological environment.Its derivatives（sulfite and bisulfite）are often added to foods,beverages and pharmaceutical products as preservatives.Nevertheless,excess intake of SO₂ derivatives can do harm to human health.Therefore,it is of great significance to develop an effective method for the detection of sulfur dioxide and its derivatives.Compared with other common detection techniques,fluorescent probe technology exhibits simple operation,high sensitivity and good selectivity.Therefore,several fluorescent probes for the detection of sulfur dioxide derivatives were designed and synthesized based on hemicyanine.At the same time,the novel fluorescent material—carbon dots were preliminarily studied in this paper.Probe Hcy-NO₂,probe Hcy-CH₃ and probe Hcy-NH₂ were synthesized based on hemicyanine for the detection of SO₂ derivatives.Their UV absorption and fluorescence spectra were recorded and analyzed.The results showed that the three probes can achieve high selective response to bisulfite,and the color of the probe solution changed immediately（within 10 s）upon bisulfite,which provides a simple way to recognize bisulfite with naked eyes.Besides,all the probes could quantitatively detect bisulfite with detection limits of 8.7μM,6.5μM and 4.0μM,respectively.Furthermore,visual detection of SO₂ gas has been successfully realized with probe Hcy-NO₂.In this paper,CD was synthesized by one-step hydrothermal method using citric acid and ethylenediamine as raw materials,and the physical characteristics and optical properties of CD were investigated.The high selectivity detection of ferric ions was realized because the surface of CD was rich in carboxyl,amino and hydroxyl groups.In order to give full play to the advantages of two types of probes and obtain a better performance probe for sulfur dioxide derivatives,probe Hcy-NH₂ was bonded to the surface of carbon dot CD to obtain CD-Hcy.Finally,the surface functional group distribution and optical properties of CD-Hcy were studied.Although the introduction of carbon dot has improved the water solubility of the probe to a certain extent,the detection of SO₂ derivatives still needs to be improved.