Identification Of Crude Oils Based On Two-dimensional Raman Spectroscopy

With the development of offshore oil and gas development and oil transportation,marine oil spills occur from time to time,causing the serious harm to the surrounding environment and marine ecology.The identification of oil spill based on chemical fingerprint not only provides a reliable basis for the legal ruling of oil spill accident,but also an effective means to prevent and deter the escape after oil spill.Conventional identification techniques of spilled oil includes gas chromatography,infrared spectroscopy,liquid chromatography,fluorescence spectrometry,gas chromatography-mass spectrometry and nuclear magnetic resonance spectrum.The composition of spilled oil is complex and difficult to identify.In order to improve the persuasiveness and reliability of identification results,it is a common strategy to adopt multiple methods.Therefore,it is highly necessary to develop new identification technology.In this thesis,fifteen kinds of crude oils were used as the model samples.The characteristic sample signals containing both fluorescence and Raman information were collected by using a micro-confocal Raman spectrometer equipped with visible(532nm)and near-infrared(785nm)excitation laser.Two dimensional synchronous correlation Raman spectroscopy and discriminant analysis methods were then used to carry out a rapid,non-destructive identification of crude oils.In the two-dimensional synchronous correlation spectra,the obvious differences of the autocorrelation peaks(2300cm-1,2300cm-1)and the cross peaks(3030cm-1,950cm-1)were observed among the different crude oils.The full-variable and the stepwise Fisher discriminant analyses based on the two-dimensional synchronous correlation spectra was carried out,respectively.The results show that the accuracy rate of identification was 94.1%for the full-variable Fisher discrimination method.In comparison,the crude oils were all identified correctly when using the stepwise Fisher discrimination method;namely,accuracy rate of identification was 100%.The combined use of one-dimensional Raman spectroscopy and two-dimensional synchronous correlation spectroscopy can increase both the persuasiveness and credibility of the identification results,which can provide an efficient technical support for the rapid identification of marine oil spills and is important for marine environment management and pollution prevention.