过硫酸钠修复土壤中多环芳烃的准确测定

多环芳烃(PAHs)是一类具有致癌、致突变、致畸的碳氢化合物，具有较高的辛醇-水分配系数，易被土壤颗粒吸附而影响环境和人体健康。过硫酸钠(Na₂S₂O₈)氧化法是近些年来国内外修复PAHs污染土壤较为常用的方法，但现阶段在测定修复后土壤中PAHs含量、进行土壤修复效果评估时亟待解决的问题是：经该方法修复的土壤，若土壤中残留有过硫酸钠，在样品前处理过程中由于提取温度较高，可能会进一步加速多环芳烃的氧化反应，从而影响土壤中PAHs的准确测定。本文建立了一种在修复后土壤中加入还原剂抗坏血酸，与残留的过硫酸钠反应生成脱氢抗坏血酸，采用索氏提取结合气相色谱-质谱法(GC-MS)同时测定土壤中16种PAHs的方法，PAHs加标回收率为76.2%～110.0%。而修复后土壤若不加还原剂直接进行索氏提取，用GC-MS测定，可能会使部分PAHs及替代物的测定不准确，PAHs加标回收率仅为6.0%～72.4%。通过对比分析表明，在样品提取前加入还原剂，可以有效地消除残留过硫酸钠的影响，提高测定修复后土壤中PAHs含量的准确性。

Accurate Determination of Polycyclic Aromatic Hydrocarbons in Soil Remedied with Sodium Persulfate

BACKGROUND: Polycyclic aromatic hydrocarbons (PAHs) are a series of carcinogenic, mutagenic and teratogenic hydrocarbons with high octanol-water partition coefficients, which are easily adsorbed by soil particles and affect the environment and human health. Sodium persulfate (Na₂S₂O₈) oxidation method to remediate PAHs in organic contaminated soil is a more commonly used method in recent years both domestically and internationally. However, at the present stage, the urgent problem to be solved in measuring the content of PAHs in the remediation soil and evaluating the effect of soil remediation is that if sodium persulfate remains in the soil, the oxidation reaction of PAHs may be further accelerated due to the high extraction temperature in the sample pretreatment process.OBJECTIVES: To develop an accurate method to determine PAHs in soil after remediation.METHODS: The effects of no reductant and pre-added reductant-Soxhlet extraction on the recoveries of 16 polycyclic aromatic hydrocarbons and 6 substitutes in soil after remediation were investigated using gas chromatography-mass spectrometry (GC-MS).RESULTS: The results showed that the method of pre-added reductant (Vitamin C) was better than no reductant. The PAHs recoveries of pre-added reductant and no reductant were 76.2%-110.0% and 6.0%-72.4%, respectively.CONCLUSIONS: The comparative analysis showed that adding reducing agent before sample extraction could effectively eliminate the influence of residual sodium persulfate and improve the accuracy of PAHs determination results in soil after remediation. This study provides a new method for the accurate determination of PAHs in soil after remediation.