The Synthesis Of Rhodamine B Derivative Fluorescence Probe And Detection Of Fe³⁺ And Al³⁺

In this paper,a fluorescent probe of rhodamine B derivatives was synthesized by two steps condensation reaction.The synthesized compounds were characterized by IR,UV and fluorescence spectra.Characterization by IR,it is found that the compounds contain N-H bonds,C=O bonds,and C-N bonds of primary amines.The compound can react with iron ions,aluminum ions and copper ions to produce fluorescence,?ex is around 558 nm,?em is around 580 nm.The minimum detection limit is 10-6mol/L.The standard curves of the interaction of the fluorescence probe with the iron ion and the aluminum ion are y=5.6492x+380.2126,0.97902;y=6.54828x+337.4165,correlation coefficient is 0.99215.Specific content includes the following three parts:(1)Synthesis of fluorescent probesWith Rhodamine B,acetyl chloride and hydrazine hydrate as raw materials,we synthesized a fluorescent probe which can detect iron ion and aluminum ion.First,preparing the intermediate product.Under the protection of nitrogen,Rhodamine B was dissolved in anhydrous ethanol and hydrazine hydrate was added.Intense stirring and back-flow with 10 h.After drying solvent,extracting the product with water and dichloromethane.Then,after drying,evaporation and so on,we get yellow product,the yield was 36%.Next,preparing probe with intermediate product.Dissolving intermediate product in anhydrous dichloromethane,and dropping the mixed solution of acetyl chloride and anhydrous dichloromethane under the cooling condition of the ice bath.And paying attention to vigorous agitation in the course of reaction.Then,adjusting PH with sodium hydroxide and hydrochloric acid.Next,after filtration,drying and so on,we get the final product-probe,the yield was 57.7 %.(2)Characterization of fluorescent probes and detection of heavy metal ionsWe used the IR spectra,the UV Vis spectra and the fluorescence spectra to analyze Rhodamine B and probe.Probe can combine with copper ion,iron ion and aluminum ion,but there is no response to cadmium ion,mercury ion,etc.Probe combines with metal ion and showed no fluorescence activity in water.However,it can reacted with copper,iron and aluminum ions to produce strong fluorescence in anhydrous ethanol.Determining the linear range from 10-4 to 10-5 mol/L,the detection limit was 10-6 mol/L and drawing the standard curve.(3)Determination of iron ion content in milk powderWe use the fluorescent probe was to detect the milk powder samples.First,we put the milk powder in the mixed nitric acid and hydrochloric acid for digesting it to clarify.Then,in high temperature digesting it to white smoke.Next,we get the sample by adding water to remove the acid,ultrafiltration,etc.By detecting the fluorescence intensity of the mixed solution of probe and sample,we got the content of iron ion was 8×10-5 mol/L in the sample.Furthermore,the iron ion content in milk powder was determined to be 0.11mg/g.Finally,we carry out the recovery test of milk powder samples.