Detection Of 3-nitrogen In Aquaculture Water Based On Raman Spectroscopy

Nitrate,nitrite and ammonia nitrogen(3-Nitrogen)are three forms of nitrogen in aquaculture water.The overmuch 3-nitrogen in aquaculture water can cause eutrophication of water,and can also break the ecological balance of water,which can make the death of fish,shrimp,crab and so on.More seriously,it can affect the yield of aquaculture and cause huge economic loss.The traditional method to detect the 3-nitrogen in aquaculture water includes spectrophotometric,electrochemical method,spectral analysis method,etc.But those methods have a lot of disadvantages which includes: low detection precision,fussy process of sample treatment,not suitable for the continuous detection of sample,etc.Therefore,scientist needs to research a rapid and accurate method to detect the 3-nitrogen in aquaculture water.The Raman spectroscopy as an easy and rapidly analysis method has been used to detect water quality more and more widely.This thesis takes the 3-nitrogen in aquaculture water as the object of study and use the common Raman spectroscopy and surface-enhanced Raman spectroscopy respectively for the detection and analysis of 3-nitrogen in aqueous water,and then we detected 3-nitrogen in aquaculture water,and achieved the quantitative detection of nitrate.Mean contents of this paper are as follows:(1)Use the integrated Raman spectrometer and the common Raman spectroscopy to detect the spectrum of nitrate,nitrite and ammonium ion respectively.By analyzing the data of spectrum,we can see that common Raman spectroscopy can detect the Raman scattering signal of nitrate ion(concentration?1mg/L),but the intensity of characteristic peak is weak.The Raman scattering signal of nitrite and ammonium ion at low concentration can't be detected,because there're so many impure peaks.(2)We use the gold sol SERS substrate to detect the 3-nitrogen in aqueous water.The results indicate that the SERS can detect the characteristic peak of nitrate better than the common Raman spectroscopy,and its intensity is several times than before.We can also see that the positon of NO3-'s Raman characteristic peak is near the 1045cm-1;the SERS signal of nitrite ion's is very weak,but we can see that the position of NO2-'s Raman characteristic peak is near 1335cm-1when the concentration is high;SERS method can't detect the Raman scattering signal of ammonium ion at low concentration in water.This method can be used for the qualitative detection of the low concentration of NO3-in aqueous water.(3)Use SERS to detect different concentration of nitrate and nitrite ion in water respectively,and the data is Processed.Then the quantitative analysis model of nitrate ion and nitrite ion in water was established with the employed of the unary linear regression method based on the SERS.The results indicate that the standard linear regression curve of different concentration of nitrate ion and its intensity of Raman characteristic peak which located in 1045 cm-1 is y=8.2333x+6772.1,R2=0.94279,and its linearity is well,and it can be used for quantitative detection;But the standard linear regression curve's(y=0.9261x+1129.9,R2=0.84696)degree of fitting of nitrite ion in water is not good,meanwhile its sensitivity is low,and it can be used for qualitative detection;The Raman signals of low concentration ammonia nitrogen can not be detected.The limit of detection is 1mg/L,and the RSD range from 4.0%-6.0% in the detection of nitrate in aquaculture water.The precision can meet the requirement of detection,and the stability is well at the concentration ranged from 1 mg/L-10000 mg/L.The quantitative determination of nitrate ion in low concentration aquaculture water using the surface-enhanced Raman spectroscopy based on the gold sol substrate is performed in this paper.