应用气相色谱法测定土壤中15种有机氯农药(OCP′s)及多氯联苯(PCB′s)。土壤样品(10 g)用正己烷-丙酮(1+1)混合液160 mL在65 ℃水浴中索氏提取4 h,所得提取液用硫酸分次进行磺化净化。净化后的溶液氮吹浓缩至0.5 mL,用正己烷定容至1 mL。分取1 μL进样,用HP-1色谱柱分离,用电子捕获检测器(ECD)检测。所测15种OCP′s和PCB′s的质量浓度均在1.0~100 μg·L-1范围内与其峰面积呈线性关系,15种化合物的检出限(3S/N)在0.080~0.16 ng·g-1之间。在空白样品中加入15种化合物的混合标准溶液10.0 ng进行回收试验,测得回收率在86.4%~108%之间,其测定值的相对标准偏差(n=7)在2.4%~5.2%之间。

GC was applied to the determination of 15 organochlorine pesticides (OCP′s) and polychlorobiphenyls (PCB′s) in soil. The soil sample (10 g) was extracted with 160 mL of a mixture of n-hexane and acetone (1+1) in a water bath at 65 ℃ by soxhlet extraction for 4 h. The extract was then purified by sulfonation through shaking with portions of H2SO4. The solution was concentrated to ca. 0.5 mL by N2-blowing and made up to 1 mL with n-hexane. An aliquot of 1 μL was introduced into the HP-1 column for GC separation. ECD was used in detection. Linear relationships between values of peak area and mass concentration of the 15 compounds were kept in the same range of 1.0-100 μg·L-1, with their detection limits (3S/N) in the range of 0.080-0.16 ng·g-1. Recovery was tested by adding 20 ng of mixed standard solution of the 15 compounds to a blank sample as matrix, giving values of recovery in the range from 86.4% to 108%, with RSD′s (n=7) ranged from 2.4% to 5.2%.