Quantitative Method of Alkyl Polycyclic Aromatic Hydrocarbons in Surface Soils of Coal Mines

Polycyclic aromatic hydrocarbons (PAHs) are one of the most concerned environmental pollutants, due to their high abundances, wide existence, and significant impacts on modern society. Long-term exposure to polycyclic aromatic hydrocarbons will increase the risk of liver cancer, lung cancer and gastric cancer. The analytical methods for 16PAHs that the US EPA has proposed for priority control in soil samples are quite mature and have been widely used for decades. However, there was few research reported on the alkylated PAHs (aPAHs) quantitation. In this work, an analytical method based on GC-MS was developed and validated for the quantitation of 51 aPAHs and 16PAHs in soil samples. Soil dichloromethane ultrasonic extractions were analyzed by GC-MS with EI source. Potential PACs mass spectra were extracted and identified by the comparison between NIST library. The quantitative analysis of the target compound was further carried out with relative response factor, which was calculated with as much as 27 standards compounds. The validation results showed that the linear correlation coefficient (R²) of 27 PAHs mixed standard were greater than 0.99 in the range of 0.05-0.8 mg/L. The spiked recoveries of the PAHs were 73.11%-119.8%, with the relative standard deviations (RSD) of 1.07%-14.3%. The surface soil samples collected from four coal mines were analyzed, and the results showed that the content of a-PAHs in the surface soil was significantly higher than that of 16PAHs. The average content of polycyclic aromatic compounds (PACs) was 24 543 μg/kg (10 606-36 414 μg/kg). Among them, the contents of a-PAHs were 26 810, 25 090, 16 301 and 7 059 μg/kg, respectively, and the total average value was 18 815 μg/kg, which was 3.3 times the average value of 16PAHs (5 728 μg/kg), indicating that a-PAHs pollution was widespread in the soil of coal mining areas and was worthy of attention. The method is simple, fast, accurate, low-cost, and suitable for the detection of a-PAHs and 16PAHs in soil samples，which creates conditions for the future study and evaluation of PAHs pollution in coal mining areas, and provides necessary technical support for overall pollution control in our country.