Cleanup procedure for contaminated oils prior to fingerprinting by gas chromatography and infrared spectroscopy

The Chemistry Branch of the U.S. Coast Guard Research and Development Center has developed and refined a system of four mutually supporting instrumental analytical methods to match waterborne petroleum oil spills to their source oils. The authors have found that two of the methods, gas chromatography (GC) and infrared spectroscopy (IR), occasionally suffer from interfering contaminants which mask the characteristic petroleum oil patterns. The common contaminants are animal or vegetable oils or their breakdown products, as well as other biological materials from sewage or sediment. These substances remain mixed with the petroleum oil even after our standard pentane deasphalting procedure. There are two well established ways of removing such contaminants. The authors explain these methods.