The Application Of Surface Enhanced Raman Scattering Spectroscopy In Defining Food Additives

Widespread usage of food additives greatly enriches the diet diversity of humans.However,the abuses of the limited additives by illegal traders would not only infringe upon the rights of customers but also pose a serious threat on consumers' health if those behaviors are unable to be supervised by the department of food regulators.Studies have shown that carmine,one of the azo pigment,can lead to DNA damage and potentially carcinogenic,saccharin is not safety enough for human intake because of its still remains controversy as food additives.Moreover,the discovery of ethyl maltol in edible oil means that the reduction of the quality and safety,consequently it may cause the headaches and emesis easily with the long term and excess intake.The consummate sample treatment processing and test facility can help us to deal with the problems in food safety without delay.At present,numerous analysis methods are available for those additives determination in food products at laboratories and include high efficiency gas chromatography?GC?,liquid chromatography?HPLC?,gas chromatography/mass spectrometry?GC/MS?,and liquid chromatography/mass spectrometry?LC/MS?,which called “gold standards” for the determination of chemical contaminants.However,those analysis methods are not suitable for the on-field tests due to some tedious pre-treatments,exorbitant operating conditions,or large-sized instruments.Therefore,it is necessary to explore a fast approach for early pre-screening in food on field or market.Surface-enhanced Raman scattering?SERS?Spectroscopy has shown the high sensitivity compared to the conventional Raman spectroscopy,which makes progress in trace samples test due to Raman spectroscopy is a powerful vibrational spectroscopic technique.The key of apply SERS to practical application is synthesis of SERS substrate.The metal nanoparticles?NPs?,such as Ag NPs and Au NPs,are used as SERS substrates widely due to its inherent plasmon mode.The stability of nanoparticles will be promoted after adding stabilizer which would prevent nanoparticles from aggregation.In this thesis,exploratory study about SERS spectroscopy is applied in the food safety testing to determine the abuse of additives,such as carmine in tea,saccharin in fresh jujube fruit and ethyl maltol in edible oil,to establish a rapid,sensitive,selective and simple testing method to further expand application area of SERS spectroscopy.The study contents and conclusions are presented as follows:1.By changing laser excitation wavelength to reduce the fluorescence background,we have successfully determine three red pigment,Rhodamine B,Rhodamine 6G and carmine under spiked test with portable Raman instrument at the same time.2.Sodium phytate was introduced to stabilize Ag nanoparticles?Ag@IP6 NPs?under the optimization process.The Ag@IP6 NPs are constructed and used as SERS substrate,yielding high Raman enhancement of R6 G.3.Fe³⁺ was introduced as intermediary to determine ethyl matol based on functionalized Au NPs.Visualization-SERS spectra dual mode method was achieved to determine ethyl maltol in edible oil.Also,the proposed easy assay of Au NPs combining with portable Raman system is simple,accuracy and high sensitivity.The results of using Raman spectroscopy technology to detect carmine in tea,saccharin in fresh jujube fruit and ethyl maltol in edible oil are relatively ideal with certain promotion significance of reality.There is no doubt that as the rapid,nondestructive and safe detection technology,Raman spectroscopy can be applied in the testing of food safety.