The Surface Reaction-based SERS Sensor Was Developed To Detect Nitrite Ions

As a rapid,non-destructive and safe detection technology,Raman spectroscopy,which collect the molecular vibration fingerprint spectra,has the characteristic of security,fast and accurate,reproducibility,simple preparation,portable and widely used,etc.Surface enhanced Raman spectroscopy(SERS)is a analytical technology which is based on Raman spectroscopy adding enhanced substrate.And it has high sensitivity and is widely applied in the detection of trace sample.Chemical reactions reacted on the phase interface are usually called surface reactions,which have various sorts.Surface chemistry developed rapidly in the 1940 s and a large number of research were put in at the same time.Development in,People studied the surface reaction from macroscopic to microscopic gradually from the late 60 s to early 70 s,making the surface chemistry develop rapidly.We choose simple surface reaction to realize fast detection of analyte with high selectivity and specificity.It also has no interferences from other substances,which is one of the advantages.This paper combines surface reaction and SERS together to develop a new type of sensor,which will be of great development in the field of analysis.In this paper,the concentration of nitrite ions in tap water,saliva and urine was detected through different surface reaction.Traditional technologies to detect nitrite ions include ion chromatography(IC),fluorescence,electrochemical,colorimetric and electrophoresis.These methods usually have the problems of e complex pretreatment and relative high sensitivity,while surface enhanced Raman spectroscopy(SERS)does not need complex pretreatment process,and it also has fast detection time,more sensitivity and lower detection limit than Raman spectroscopy(RS).Surface enhanced Raman spectroscopy provides the molecular fingerprint information and plays an important role in the analysis of the trace sample detection,so we combine the surface reaction and surface enhanced Raman spectroscopy technology together to detect the concentration of nitrite ions.Surface enhanced Raman spectroscopy need gold nanoparticles and silver nanoparticles used as active substrate to enhance SERS signals.Metal nanoparticles has its intrinsic surface plasmon resonance effect,while silver nanoparticles have more enhanced effect.At the same time,we can also add the protection agent and stabilizer to prevent agglomeration of nanoparticles to improve the stability of the nanoparticles.In this paper we made tentative exploration and combined surface reaction and surface enhanced Raman spectroscopy together to detect the nitrite ions in tap water,saliva and urine respectively to establish a quick and easy detection method to further expand the application range.The main research contents and results are as follows:1.P-aminothiophenol(PATP)and nitrite ions could trigger azo reaction under acid condition to detect the nitrite ions in tap water.SERS spectroscopy had obvious changes before and after the reaction and normalize the three characteristic peak at 1148 cm-1,1394 cm-1,1439 cm-1 respectively of the N=N compound.It had a good linear detection range from 25?M to 125?M,satisfied the national standard 200 parts per million(PPM)in our country and the world health organization(WHO)214.2?M.The correlation of three characteristic peaks(R2)are 0.98274,0.96771 and 0.98937 respectively.The recovery of the spiked practical samples are between 95.67%and 103.96%in tap water and the recovery is relative good.2.Urea and nitrite ions could trigger diazo reaction under acid condition to detect the nitrite ions in saliva.There is only one characteristic peak of urea in 1003 cm-1.The intensity of peak reduce sharply after the reaction.Normalize the peak and the nitrite ions had a good linear relationship from 20?M to 120?M.The correlation of characteristic peak(R2)is 0.96498.The recovery of the spiked practical samples are between 82.23%and 89.93%in saliva and the recovery is relative good.3.a-naphthylamine,aminobenzene sulfonic acid and nitrite ions could trigger azo reaction under acid condition and color is visual changes from the naked eye,which can watch the reaction occured more directly.It had a good linear detection range from 5?M to 100?M.The correlation of characteristic peaks(R2)are 0.97543 and 0.96822 respectively.The recovery of the spiked practical samples are between 93.5%and 102.66%in tap water and the recovery is relative good.In this paper we combined the surface reaction and the surface enhanced Raman spectroscopy together to detect nitrite ions effectively.The sensor made with this method is fast and easy to detect and also has excellent selectivity.The sensor based on surface reaction would develop rapidly in food and environment field.The human life would have further protection due to it.