| PAHs (Polycyclic aromatic hydrocarbons) refers to two or more benzene rings connecting to form fused ring compounds, it is a class of the cancer-causing organic pollutants, and widely present in the environment. PAHs in the atmosphere is harmful to human’s heath, so the development of convenient, reliable and sensitive monitoring of PAHs is extremely important to improve the air pollution, and ensure human’s health.At present, PAHs can be sampling by active sampling and passive sampling. Active sampling is used to collect atmospheric particulate matter samples. Its sampler is expensive and complicated. Besides, it have to take a long time continuous operation. So it is not suitable for a wide range of field sampling and simultaneous sampling study. Passive sampling is used to analyze the gas organic compounds in the air. It can work without power and make no noise. It is commonly used in environmental testing of the supervisory. Many leaves have a pore structure and the surface covered with a layer of the cuticle which can accumulate fat-soluble organic compounds in the atmosphere. They had been widely used as passive samplers and instructed the pollutant levels of PAHs in the air. Needles is used as a typical passive samplers because of its widely distribution, and it can be collected easily. Besides, it can concentrate the pollutants for a long time. Based on the literature, the needle sample pre-treatment technology is established. The study also establish a technology can extract fastly Phenanthrene(Phe), Anthracene(Ant), Fluoranthene(Fu), Pyrene(Pyr), Benzo[a]anthracene(BaA) and Chrysene(Chr) in pine needles which are sampled from two place in Chengdu University of Technology.The analysis method is established to determine Phe, Ant, Fu Pyr BaA and Chr by gas chromatography.The conditions of simultaneously to determine Phe, Ant, Fu Pyr BaA and Chr are optimized:The speed of mobile phase(N2) is5ml/min; Gasification temperature is290℃; Detector temperature is300℃; Column-box temperature use temperature-programmed; Keeping3min at180℃, then rising to230℃at6℃/min and keeping3min, last rising to250℃at10℃/min; The speed of tail-blowing is30ml/min; FID; Capillary column; FID; The handing quantity is0.2μl.The study finalized the best extraction conditions by investigating the three experiments affect including the solvent, ultrasonic power, extraction time. It is: temperature of25℃; ultrasonic power of100W; extraction solvent Vhexyl hydride:VCH2C12=2:3extraction time of90min. In this experiment, a silica gel purification column is home-made. Its purification performance is examined by elution of the standard solution. It showed that the recovery rate of Phe, Ant, Fu Pyr BaA and Chr is in line with the experimental requirements. The eluent of n-hexane.The study analyzes the pine needles which are sampled from two different place in Chengdu University of Technology. Phe, Ant, Fu, Pyr and Chr has been detected while BaA hasn’t. The content of Phe, Fu and Pyr is higher, the content of Ant and Chr is lower. The concentration from two place is different. It shows that the pine needles sampled from the traffic area has a higher concentration than the pine needles sampled from non-traffic area. Indicate the source of PAHs by the ratio of Phe/Ant. The results show that the main source of PAHs in pine needles is from the automotive exhaust. Concentration of PAHs in pine needles sampled at April is higher than the concentration in pine needles sampled at July. It is because of the volatilization and photodegradation of PAHs by heat and light. |
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