Detection Of Cu Ions Based On SPR Sensor Modified By Chitosan

In this thesis,SPR sensing technology and adsorption on heavy metal ions with chitosan are combined to detect Cu ions in solution,which has the advantages of high sensitivity,fast detection and good repeatability.The necessary conditions of SPR are explained in theory,especially according to the definition of SPR and the total reflection theory,the condition that the total reflection is necessary for the generation of SPR in the prism coupled structure is deduced by comparing the three–layer and two-layer structure.The principle of angle modulation detection and intensity modulation of SPR sensing technology and the mechanism of chitosan adsorbing Cu ions are introduced.The optimal parameters of Ag/Au composite film obtained by MATLAB simulation are 30nm for Ag film and 15nm for Au film.In comparison with the Cr/Au composite film,the half peak width and the minimum reflectivity of the angle scan curve,the sensitivity and the linear range of the angle modulation detection are all improved.And the sensitivity of the intensity modulation detection is increased by about 1.67 times.A film,which is made up of the crosslinking of chitosan and glutaraldehyde,is prepared on the Au film by spin coating,on which the effects of the dosage of various reagents,the speed and time of the spin coating,the amount of glue and other factors are analyzed,and finally a good film is obtained.SPR sensor based the Ag/Au composite film is used to detect copper ions with chitosan.The results show that some chitosan on the new chitosan film substrate is easy to fall off and easily washed away by deionized water,but most of the unstable chitosan can be removed after two-times flushing.The chitosan will dissolve or swell in the deionized water,the rate of dissolution or swelling will decrease with the increasing of the washing times,while the chitosan combined with Cu ions is insoluble and stable.The EDTA solution has good elution performance for Cu ions in chitosan,and the reusability of chitosan is good.After 5 times of elution,the capacity and reusability are above 96%,and EDTA with a concentration of 0.5-10mmol/L almost has the same elution effect.The elution time is about 300s.There is a good linear relationship between the concentration of Cu ions and the signal value.The detection range for Cu ions is 0-5 ppm with a sensitivity of 0.747ppm^-1 and detection limit of 6ppb.