按DD 2008-01规定采集浅层地下水样品并于4℃保温箱中保存。取水样1.000 0 L置于分液漏斗中，依次加入氯化钠20.0 g，1.0 mg·L^-1替代物混合标准溶液100 μL和正己烷-二氯甲烷（1+1）混合萃取液60 mL，萃取10 min，分层后，取有机相并保留，再用正己烷萃取2次，每次用30 mL。合并3次萃取液，旋转蒸发至体积约为2~3 mL，随即改用吹氮蒸发至约剩0.8 mL，加入2.0 mg·L^-1内标混合标准溶液100 μL，用正己烷定容至1.0 mL。用Rxi-5Sil MS毛细管色谱柱选择初始温度为65℃，按程序升温条件进行气相色谱分离；质谱分析采用电子轰击离子源，全扫描模式定性和选择离子模式定量。结果表明：36种多环芳烃及其衍生物的质量浓度在一定范围内与其峰面积呈线性关系，检出限（3S/N）在1.3~8.8 ng·L^-1之间。以空白水样为基体进行加标回收试验，回收率在71.1%~120%之间，测定值的相对标准偏差（n=5）在1.2%~9.7%之间。

Samples of shallow groundwater were collected and stored at 4℃ in a refrigerator according to DD 2008-01. 1.000 0 L of the water sample was taken, and extracted for 10 min with 60 mL of a mixed extracting solvent of n-hexane and dichloromethane (1+1), after successive addition of 20.0 g of NaCl and 100 μL of 1.0 mg·L^-1 standard solution of mixed substitutes. After the 2 phases were separated, the organic phase was separated and preserved, and the water phase was extracted twice further with 30 mL of n-hexane for each extraction. The 3 extracts were combined and evaporated under swirling until its volume was concentrated to 2-3 mL, the evaporation was continued by N₂-blowing to concentrate the solution to a volume ca. 0.8 mL. 100 μL of the 2.0 mg·L^-1 mixed internal standard solution was added and the volume of the solution was made up to 1.0 mL with n-hexane. Rxi-5Sil MS capillary chromatographic column was selected for GC separation, under temperature elevation program by choosing 65℃ as the initial temperature. In MS analysis, EI ionization source was used, and mode of full-scanning was adopted for qualification while the mode of SIM for quantification. As shown by the results, linear relationships between values of peak area and mass concentration of the 36 polycyclic aromatic hydrocarbons and their derivatives were found in definite ranges, with detection limits (3S/N) in the range of 1.3-8.8 ng·L^-1. Test for recovery by standard addition method was made on the base of blank water sample, giving results in the range of 71.1%-120%, and RSDs (n=5) ranged from 1.2% to 9.7%.