The Study On Chemical Fingerprint Identification Of Crude Oil Spilled On The Sea

As unique as the human fingerprint, the physical properties and chemical compositions of crude oils are inherent. These unique characteristics are called "oil fingerprint". It is a important significance to study "chemical fingerprints" of different kinds of crude oils for distinguish oils by means of analytical instruments.Based on a large number of crude oil leak into the sea due to the incidents increase of marine oil spilling in recent years, it is very necessary to find a rapid and accurate method to trace the leak sources of crude oils, to protect the marine environment, to investigate responsibility of the wreckers, and to enrich the database of oil fingerprint. According to the characteristic of crude oils, gas chromatography/flame ionization detector, isotope ratio mass spectrometry, high performance liquid chromatography, synchronous fluorescence spectrometry and flame atomic absorption spectroscopy was used to analyze n-alkanes (including n-C10～n-C24,pristane and phytane), stable isotope ratio mass of carbon(13C/12C), petroporphyrins, polycyclic aromatic hydrocarbons and ratio of nickel to vanadium in Daqing and Kuwait crude oil before and after weathering, respectively. Attempt to find out the parameters which are provided with interior characteristics of crude oils. These parameters were combined together to constitute the chemical fingerprints of crude oils, in order to provide technical supports for identification of spilled oils.The experimental results as follows:In the pretreatment of oil samples for gas chromatograph analysis, reagent grade silica gels were chosen as chromatographic stationary phase, methylene chloride:n-hexane=2:1 (v/v) were chosen as the eluent. These optimization conditions had good separation effect on n-C10～n-C24, Pr and Ph; gas chromatography results showed that differences of n-C17/Pr and n-C18/Ph are obvious, and the variation of n-C19～n-C22 contents are little before and after oils weathered, their RSD are less than 5%, namely, n-C19～n-C22 are less affected by weathering. Therefore, n-C17/Pr, n-C18/Ph and n-C19～n-C22 can be used as fingerprint parameters of n-alkanes to distinguish the spilled oils; Synchronous fluorescence spectrometry was used to analyze PAHs in crude oils, the fluorescence spectra between Daqing and Kuwait crude oils are clear difference; Assistant GC analysis also showed that weathering has almost no influence on PAHs with heavier molecular weight. These components can be used as parameters to indicate oil characteristic; based on the results of isotope ratio mass spectrometry,δ(13C/12C) of n-C17～n-C21 between Daqing and Kuwait oil has significant difference, but these values were little affected by weathering. Therefore,δ(13C/12C) can be used as a parameter to distinguish spilled oil; As results of high performance liquid chromatography, the contents of porphyrins are obviously different between Daqing and Kuwait oi; The ratio of Ni to V had significant difference between Daqing and Kuwait oil, and this ratio was not almost affected by weathering. It can also be a characteristic parameter of oil.