Evaluation of Detection Performance of Turbidity Analysis for Alcohol-extracted Hydrocarbons by Comparison with Other Analytical Methods for Petroleum in Soil Samples

Petroleum hydrocarbons scattering over the surface and the subsurface environment give degradation of the quality of soil and water resources, resulting in substantial health risks to the human beings, plants and animals. To remove petroleum from the ground, it is supposed that the petroleum be extracted directly from the site or the ground be remediated by decomposing petroleum using oxidizing agents. However, a problem involved in the work is to know how large and deep it is in the ground when taking care of petroleum as a pollutant in the ground. It is important to effectively track petroleum leaked into the environment in a simple and quick manner. On–site screening methods have been desired, therefore, across the world for wide application to the inspection of hydrocarbon contaminants in soil. We already reported an easy method based on a turbidity analytical technique to quickly and semi–quantitatively detect organic compounds through a simple procedure using ordinary chemicals and common equipment at a site (Sakai et al., 2011). Organic compounds can be detected at concentration levels of 2,000 to 15,000 mg kg –1 . The indication of the presence of petroleum suggests that the ground be polluted with the pollutant at the site. But the performance could be influenced by a variety of factors such as soil properties or texture, water contents and chemical characteristics of petroleum in soil samples. In this study, we compared the performance of the turbidity analysis with that of two other methods commonly used in laboratories or gravimetry and gas chromatography–flame ionization detection (GC–FID). We also evaluated the ability of a turbidity analysis–based screening method using a typically available test–kit in the market based on the turbidimetry analytical principle.