Kim Tae-Kyoung, Lee Donghyun, Walsh Griffin, Lee Changha, Sedlak David L
Department of Civil and Environmental Engineering, University of California, Berkeley, California 94720, United States.
School of Chemical and Biological Engineering, Institute of Chemical Process (ICP), and Institute of Engineering Research, Seoul National University, Seoul 08826, Republic of Korea.
J Hazard Mater Lett. 2024 Nov;5. doi: 10.1016/j.hazl.2024.100102. Epub 2024 Feb 1.
To assess the performance of hazardous waste sites remediation technologies, like in situ chemical oxidation (ISCO) with persulfate ( ) researchers must periodically measure concentrations of target contaminants. Due to the presence of relatively high concentrations of the residual oxidant expected in many samples, the standard analytical method requires the addition of a relatively high concentration of ascorbic acid to prevent the oxidation process from continuing after sample collection. We discovered that addition of ascorbic acid quencher results in a radical chain reaction that transforms two common halogenated solvents (i.e., tetrachloroethene and hexachloroethane). To avoid the artifact associated with the radical chain reaction, a small quantity of n-hexane can be added to aqueous samples to extract target compounds and protect them from the radical chain reaction initiated by addition of the quencher. We recommend the use of this alternative sample preservation method whenever high concentrations of residual are expected to be present in water samples that are contaminated with halogenated solvents.
为评估危险废物场地修复技术的性能，例如过硫酸盐原位化学氧化（ISCO），研究人员必须定期测量目标污染物的浓度。由于许多样品中预计会存在相对高浓度的残留氧化剂，标准分析方法要求添加相对高浓度的抗坏血酸，以防止样品采集后氧化过程继续进行。我们发现，添加抗坏血酸淬灭剂会引发自由基链反应，该反应会转化两种常见的卤代溶剂（即四氯乙烯和六氯乙烷）。为避免与自由基链反应相关的假象，可向水样中添加少量正己烷以萃取目标化合物，并保护它们免受淬灭剂添加引发的自由基链反应的影响。我们建议，当预计被卤代溶剂污染的水样中存在高浓度残留过硫酸盐时，使用这种替代的样品保存方法。
