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Resonance Raman Spectroscopy And Its Application In The Detection Of Additives In Seafood Meat

Posted on:2020-06-28Degree:MasterType:Thesis
Country:ChinaCandidate:B B XuFull Text:PDF
GTID:2381330578480127Subject:Optical Engineering
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Laser Raman spectroscopy has the characteristics of fast,non-invasive and in-situ detection,and it is widely used in the detection of molecular fields.Resonance Raman spectroscopy(RRS)and surface-enhanced Raman spectroscopy(SERS)have been favored by researchers for their unique advantages,and widely used in various fields.The work of this paper mainly includes the following two parts.The first part is a review of the application development of resonance Raman spectroscopy.The absorption intensity of the incident light is greatly increased due to the frequency of the excitation light source falling in one electron absorption band of the molecule,resulting in a molecular transition to an electron excited state,and a resonance absorption phenomenon occuring.RRS can increase the signal intensity by a factor of 10~6compared to conventional Raman spectroscopy.Therefore,it is more widely applied with its higher sensitivity and selectivity,especially in the fields of biology and medicine.For instance:(1)pigments analysis such as chlorophyll et biological matrices;(2)substances researches such as cells and DNA,as well as the diagnosis of some clinical diseases.RRS can present some molecular information which is hidden,and even extremely important.Its detection limits is very low,so it is often used in the detection of biological substances and pigment materials.In recent years,RRS has been innovated and extended such as the application of new technologies of Liquid-core optical fiber ResonanceRaman spectroscopy and Transmission Resonance Raman spectroscopy.This part summarizes the papers and related conclusions about the application of RRS technology in recent years,and introduces the historical background and research status of RRS.And analysis the application of resonance Raman spectroscopy in the fields of dye detection,bio-detection and explosives detection in detail.Providing scientific researchers with a better understanding of the advantages of resonance Raman spectroscopy and a relatively complete reference database for for them in future research in this area.For the second part,a large number of seafood products on the market contain food additives.Investigating and deal with the use of illegal additives and additives abuse have become a key task in food safety monitoring.It is imperative to establish an efficient,convenient and sensitive method for detecting food additives.This section explores the banned additives in seafood based on Raman spectroscopy.Raman detection was carried out on ten kinds of additives such as carmine,malachite green and sodium benzoate by 532,633 and 785 nm excitation light,including:(1)Raman detection of ten kings of pure samples of malachite green,carmine red and chloramphenicol by three kinds of excitation light,and summarizing the relative intensity of characteristic peak and peak position of each additive to finding the best excitation wavelength of the most specific additive sample and determining the effectiveness of resonance Raman effect under the optimal wavelength excitation.The study found that the best detection excitation wavelength for malachite green is633nm,the best detection wavelength for carmine is 785nm,and the optimal detection wavelength for chloramphenicol is 532nm.Likewise,the optimum excitation wavelength for other additives are determined.Resonance Raman effect will appear under the corresponding optimum excitation wavelength of each additive.At this point,their characteristic peak information has changed.The specific performance is as follows:the peak intensity of the characteristic peak is greatly enhanced,and the position of characteristic peak almost all shifts,and new characteristic peaks will appear.The Raman fingerprint of each additive is unique,and the Raman spectra under three different excitation conditions are basically the same.This prove that Raman spectroscopy is very suitable for the detection of additives,and the specific excitation conditions will cause resonance enhancement in the additive detection.(2)Preparing standard aqueous solution samples of different concentration of ten additives,and the concentrations are 1,10,50,100?g/L.Raman detection was carried out on the additive samples with different concentration by using three different excitation lights of 532nm,633nm and 785nm lasers,Raman detection of the interaction between SERS and RRS showed that SERRS was very effective for the Raman detection of water samples at very low concentration(1?g/L).(3)Raman detection of the additive extract which is from meat by three different excitation lights.Comparing the Raman spectra of the additive standard solution and the additive extract from the meat,it was found that the Raman signal of the additive extract from the meat was lower than the Raman signal of the additive standard solution sample.The main reasons for this phenomenon are as follows:Firstly,the additive is lost when it is extracted from the meat,and it is also interfered with by other non-target components(such as fat and protein)extracted from the fleshy tissue,so that the additive can not be adsorbed well on the SERS substrate.Secondly,the extracted additive molecules are affected by non-target substances,resulting in a change in the adsorption state on the SERS base,which in turn causes the Raman signal of the additive extract to be not well displayed.And resulting in a decrease or disappearance of the relative intensity of the characteristic peaks.The experimental results prove that SERS and SERRS technology have practical feasibility and wide applicability in the determination of food additives.
Keywords/Search Tags:food additives, Resonance Raman, Surface-enhanced Raman, Surface-enhanced Resonance Raman
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