| Auramine O is an aromatic amine industry dye, mainly for paper, linen, leather,cotton and other industrial dyeing. The contacting or inhalation of auramine O bypeople can cause poisoning, and for its difficulty of naturally degrade in the humanbody, the residual will causes bad effect such as toxicity, carcinogenicity andmutagenicity. Early in2008the Ministry of Health has classified it as non-foodsubstances, but with the lack of accurate and reliable means of detection and therare of related reports at home and abroad, makes it difficult to detect auramine Orapidly and accurately. The existing detection methods are high-performance liquidchromatography and its combination with solid phase extraction or massspectrometry, for their complex and expensive equipment, high technicalrequirements of the operator, and long testing cycle, it is not conducive to rapidon-site testing.Raman scattering is an intrinsic property of the material, with itsfingerprint-like spectral feature, makes the qualitative detection of the samplecapable. The weak Raman signal of the sample molecules adsorbed on the SERSactive metal surface can be amplified millions of times by SERS (Surface EnhancedRaman Scattering, SERS), making the SERS technique get extreme high sensitivity.With the capability of detection on the molecular level in real time, qualitative andsemi-quantitative detection, with the capability of detection on the molecular levelin real time, qualitative and semi-quantitative detection, SERS has great potential infood safety detection.This paper presents the results of experimental studies on auramine O. SERStechnique is adopted to detect the auramine O in beancurd skin, which provides arapid pigment detection method in bean products. Firstly, the SERS active substrateof gold and silver colloids were synthesized by citrate-reduced chlorauric acid andsilver nitrate respectively, with a majority of sphere and good monodispersion.Thenapplying Gaussian software, the Raman spectra of auramine O was calculated, andits Raman peaks were assigned and identified, then compared to its normal Ramanof solid and aqueous solutions. By contrast the normal Raman of the auramine Opowder and aqueous with the SERS of the auramine O aqueous and the extract ofthe beancurd stick, besides with the reference reports, the peak of776.5cm-1(C-Hout-of-plane bending mode) was registered as the characteristic peak of auramineO.Next, the SERSs of auramine O aqueous with respectively active substrate ofgold and silver sol are studied, optimizing the test parameters to get their each limit of detection(LOD) and enhancement factor(EF). The optimal detection parametersof gold sol are: auramine O aqueous: gold sol=1:5(v/v), PH=11, and thecorresponding LOD is0.5ppm, the EF is1.86×103. The optimal detectionparameters of silver sol are: auramine O aqueous: gold sol=1:6(v/v), PH=2.1, theaddition proportion of1M nitric acid or1M sodium chloride solution were6.67%and3%(v/v)to the mixture of auramine O and silver sol, with the correspondingLOD of0.1ppm, and each EF of3.01×103and4.17×103. Finally, With referenceto the solid phase extraction and the liquid chromatography, the beancurd stick waspretreated to extract the auramine O in it. Adopted silver sol, with the higher EF, asthe SERS active substrate to detected, the LOD is10ppm. |
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