On The Spot Identification Technology For Adulteration Of Different Oils

In view of the widespread adulteration of different oils and fats in the market,a kind of on-the-spot identification technology of adulteration of different oils and fats based on UV dynamic spectrum absorption signal is studied in this paper.Based on the dynamic UV spectra of oil samples,the characteristic values for oil identification are summarized from two aspects of differential wavelength timing increment spectrum and differential wavelength dynamic parameters,and then the identification model is established and tested.(1)The timing(20 min)absorption spectrum in the dynamic spectrum signal matrix of oil was extracted,and the incremental signa△A,standardized incremental signal R△A,first derivative incremental signal D△A,standardized first derivative signal RD△A were obtained after preprocessing.PCA was used to extract the principal component of the difference band in the preprocessed signal,and the principal component value was used as the identification eigenvalue of oil.The results showed that two principal components were extracted from the R△A signal of260-340 nm,which could effectively distinguish flaxseed oil(FO),perilla oil(PSO),peanut oil(PNO),soybean oil(SO),rapeseed oil(RO)and palm oil(PO)from 30 oil samples;one principal component was extracted from D△A signal of 318-325 nm,which could effectively distinguish ro doped PNO The detection limit of identification can reach 4.8%,and the detection limit of identification can reach 3.9%by extracting one principal component from signal D△A in 285-292 nm band.(2)In the work of this chapter,based on the dynamic amplitude ratio of UV spectrum signals between different oils and the same oil,the different wavelengths which can be used to identify oil products are selected.The kinetic constants of different wavelengths are obtained by numerical fitting,and the kinetic constants are used as the eigenvalues of oil products identification.The results showed that FO,SO,RO,PNO,PO and CSO could be distinguished effectively by the standard kinetic constant K2R△A304nm,and FO,PO and RO could be distinguished effectively by the kinetic constant K1R△A320nm and K1R△A270nm.For CSO doped RO,the detection limit can reach 11.7% using K2R△A304nm as identification feature,and for CSO doped PO,the detection limit can reach 10.1% using K2R△A304nm as identification feature.The method of oil dynamic UV spectrum signal processing and identification eigenvalue extraction established in this study can support the development of oil identification software for scanning spectrometer;the identified wavelengths can provide the basis for the light source selection of multi wavelength array spectrometer,so as to provide the technical basis for the popularization of heterogeneous oil doping identification methods and equipment.