Research On Detection Of Typical Toxic Substances In Food By Terahertz And Mid-Infrared Spectroscopy

With the development of science and technology and human pursuit of high quality of life,food safety issues have gradually become a common topic of social concern.The richness of food safety testings provide a good barrier for people's healthy life and can reduce the damage to the human body from toxic substances in food.This thesis studies and analyzes two kinds of classic poisonous substances in food which are plasticizer and antibiotic through fourier transform infrared spectroscopy(FT-IR)and THz-TDS.This study collects the spectrums of the DBP and classic antibiotic(chloromycetin)to get their characteristic spectrums.This thesis utilizes the software of Gaussian 09 to conduct a theoretical simulation of molecules of additives and compared it with experiment results to analyze and confirm the types of the substances.Combined with two-dimensional correlation spectra and partial least squares method(PLS),this thesis conducts a qualitative and quantitative analysis of poisonous objects.This thesis studies as follows:(1)The thesis also separate the overlapping peak of unidimensional spectrum to obtain spectral information with high resolution.Indicating the characteristic peaks which are sensitive to the concentration of the toxic substances.This thesis utilizes the software of Gaussian 09 to conduct a theoretical simulation of terahertz spectrum vibration of molecule and assigns the infrared spectra of molecule to obtain its characteristic peak of terahertz vibration.These can provide evidence of experiment results and strengthen the reliability of the experiment results.(2)To conduct a modeling analysis of spectroscopic data obtained through PLS.According to the theory of principal component analysis,by choosing the frequency band,got the results of the modeling of DBP/sesame oil were R~2=0.9882 and RMSEV=0.3%.The optimal modeling results of chloramphenicol mixed system got three principal components,and R~2=0.960,RMSEC=0.96%,RMSEP=0.99%.This thesis models and chooses the optimized modelling to make a quantitative analysis,which suggests that PLS has a prospect of application in the field of food safety.