Study On Pretreatment Method Of Semi-volatile Organic Compounds In Soils

In recent years, along with the rapid development of modern industry and agriculture, the use of organic solvent, plastic, latex and pesticide, the leak of petroleum during the oil field exploitation and the leakage of the landfill leachate have made the soils polluted seriously. And they also have made organic pollutants in soils more complex and the concentrations higher. The pollution of soils affects the whole environment-system and human health directly. So it becomes the concern of government and public. The organic pollution of soils is an environmental problem that can not be ignored, but it has been restricted by the analytical technique of organic compounds in soils. The analytical technique is critically important to monitor and prevent the pollution of soils and to understand the soils pollution status. And it can also provide scientific foundation for constituting the correlative law.Based on domestic and overseas research, organochlorine pesticides (OCPs) and polycyclic aromatic hydrocarbons (PAHs) were selected to study. Our study compared the difference of some pretreatment methods, surge extraction, soxhlet extraction and ultrasonic extraction. To get the effective way, acetone and hexane (v/v=1:1) were selected as solvent, and then some different methods were studied in different time. The results showed that ultrasonic extraction was the best pretreatment methods with 20min for 3 circles. To find out the suitable solvent, acetone, carbinol,hexane, cylohexane and dichloromethane were studied. The results indicated acetone and dichloromethane (v/v=1:1) has stronger extraction- ability. So ultrasonic extraction with 20min for 3 circles and hexane and dichloromethane (v/v=1:1) were selected as the pretreatment methods of soils. The reclaimed ratio of this method could extend to 55%～120%. The detection limit could extend to 0.01ng/g–1.10ng/g. And basically, these could meet the needs of our demands.GC/MS can provide abundant information about organic compound structures and has super qualitativety. It is extremely meaningful to find the organic pollutants in soils. And it can qualitatively and quantitatively analyze the target compounds with high sensitivity and good selectivity. So the methods are confirmed as the identifiable method of trace semi-volatile organic compounds (SVOC) in soils by ultrasonic extraction and gas chromatography/mass spectrometry. The method is high efficient and fast. The calibration curves of the methods are in good linearity, the detection limit is low.In this thesis, the methods for conducting research and monitoring the organic pollution in soils were established in China. All of those will help to lay the foundation for the further studies on organic pollution in soils in the future.