土壤中五氯酚含量的放射性内标分析方法

Determination of pentachlorophenol in soil with radioactive tracer as internal standard

五氯酚(PCP)是一种环境内分泌干扰物,曾被广泛使用并残留在土壤环境之中.土壤中存在的五氯酚可以在酸化后采用乙酸乙酯法进行提取,使用高效液相色谱或者气相色谱进行定量分析测定,但是由于土壤的有机质背景比较复杂,当待测物PCP浓度较低时,提取液中的杂质对待测物的测定干扰极大,因此必须对土壤样品提取液进行净化.参考文献中相关方法之后,实验优化了PCP提取与测定的方法和条件,使用自制的硅胶柱对样品进行净化,利用乙酸乙酯和正己烷作为洗脱剂对样品进行梯度洗脱.和传统的内标物不同,本研究中采用14 C-放射性标记的PCP作为内标以定位净化过程中PCP的流出组份和测定样品回收率.结果表明,14 C-内标法的PCP回收率达94.3%±2.9%,净化样品可用于HPLC测定,检出PCP的最低可测浓度达到6.7μg/kg土壤.相比于以13 C-PCP作为内标的气相色谱法,14 C-内标法的分析步骤简单而又快速,实现了土壤中低浓度PCP残留的快速准确测定,为研究PCP土壤中的归趋和转化提供了新方法.

Pentachlorophenol（PCP）is an endocrine disrupting compound, which has been widely used and caused severe soil contamination. PCP in soil can be extracted with ethyl acetate;however, the determination of PCP by high performance liquid chromatography or gas chromatography may be strongly disturbed by the complexity of soil matrixes and impurities in the soil extract,especially when the PCP concentration in soil is low. Thus,a purification of the extract is needed to remove the impurities. In the present study, according to references, a method for determination of PCP in soil was optimized. A self-prepared silica gel column was used for sample purification,and PCP was eluted with a gradient mixture of ethyl acetate and hexane. Radioactive ^14C-labeled PCP was applied as inner standard to localize PCP fractions during the elution and to quantify the recovery of PCP during the sample pretreatment process. After this purification, recovery of PCP was 94.3%±2.9% and PCP in the extract can be easily determined by HPLC with a lowest detected concentration of 6.7 μg/kg dry soil. The ^14C tracer combined to HPLC determination was demonstrated to be a rapid and alternative method for soil PCP analysis to gas chromatog raphy,which requires a tedious purification procedure and ^13C PCP as inner standard.