Use Of Surface-enhanced Raman Spectroscopy For Detection Of Azodicarbonamide And Some Pigment In Food

The current food safety events have shown that the contraband added synthetic dyestuffis becoming the source of the high incidence of food safety incident, such as Ponceau4Rwhich added in the bacon and Chrysoidine which found in the dried beancurd sticks. Foodindustry has huge consumption and it’s also a FMCG industry. These characteristic make ithard to monitor comprehensively and in time. Therefore, rapid detection technology of foodcontraband pigment is in need. In recent years, Surface-Enhanced Raman scattering （SERS）technology, has gradually applied in food safety testing, as a high resolution, high sensitivity,and convenient detection technology. The objective of this study was to investigate thefeasibility of using SERS method for rapid detection of Ponceau4R, Amaranth, Erythrosine,Allura Red, Sunset yellow, Lemon yellow, and Chrysoidine.Azodicarbonamide is widely applied in the food industry as a new flour gluten fortifierin China, Canada, the United States, and some other countries.However, the applicationamount is strictly restricted because of its toxic metabolite–semicarbazide.Firstly, the structure of Sunset yellow, Lemon yellow and biurea were optimized usingDensity Functional Theory （DFT） and software Gaussian09, then the theory Raman spectra ofSunset yellow and biurea were calculated. The main characteristic peaks at984cm^-1、1092cm^-1、1242cm^-1、1476cm^-1as the fingerprint-like peaks of biurea and the main characteristicpeaks at1224cm^-1、1330cm^-1、1380cm^-1、1592cm^-1of Sunset yellow were conformed.Secondly, the gold nanoparticles and silver nanoparticles were prepared through citratereduction method, meanwhile the SERS method coupled with active gold substrates has beenapplied for detection of biurea.Then the gold nanoparticles, silver nanoparticles, andmicroporous membrane （pore size is0.22μm） were used to prepared a novel SERS activesubstrate. After that R6G was used as probe molecule to test the effect of the SERS substrate.And silver-coated PVDF millipore filtering film was confirmed to be effective and was usedin subsequent experiments.Then we detected Ponceau4R, Amaranth, Erythrosine, Allura Red,Sunset yellow, Lemon yellow, Chrysoidine respectively.The SERS spectrums of thesesynthetic dyestuff are matched with their Raman spectrums very well and the limit ofdetection of them has reached1μg/mL.The mixed dyestuff solution were also initiallyexplored in this experiment. The Raman spectra were recorded with a portable Ramanspectrometer, using50mW–300mW of the785nm laser line and5s^-10s integration times.Finally, the SERS technology was applied in detecting synthetic dyestuff in cayennepepper qualitatively. The results were agreed with that by HPLC-UV method. It isdemonstrated that the SERS technology is potential to apply in the rapid screening of thecontraband added synthetic dyestuff.