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Rapid Extraction Of Sediment Contaminants By Pressure Cycles

机译：通过压力循环快速提取沉积物污染物

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Sediment contamination is a significant issue. Assessment, management, and monitoring of contaminated sediment require routine analyses of a large volume of sediment samples, which require significant preparation time including extraction of contaminants from samples prior to analysis. This work tested a new method of extracting contaminants from sediment based on the use of rapid, successive pressuriza-tion cycles, which involve compression of a gas into the extractive solvent in contact with the sediment immediately followed by decompression via venting. The technique improved extraction amounts and shortened preparation time. Tested were PCB and PAH contaminated sediment samples from various locations of the US, including the Passaic River, St. Louis River, Waukegan Harbor, and Wells National Estuarine Research Reserve. The results were compared to those of Soxhlet extraction. Specifically, the extraction of 15 g of sediment with 50 mL of hexane-acetone (1:1) mixture at room temperature using 10 rapid, successive pressure cycles with N_2 attaining 1.0 MPa during compression was complete within 15 min. Using the new technique, consistently more PAHs and PCBs were extracted from the sediments in comparison to Soxhlet extraction. Extraction was evaluated according to key factors including the number of compression-decompression cycles, compression pressure, sample amount, moisture, and pressurizing gas type. The heightened extraction performance was explained by cyclic changes in gas solubility during repetitive compression and decompression steps, which introduce mechanisms to fragment sediment aggregates resulting in increased contaminant exposure and extraction.
机译：沉积物污染是一个重大问题。评估，管理和监测受污染的沉积物需要对大量沉积物样品进行常规分析，这需要大量的准备时间，包括在分析之前从样品中提取污染物。这项工作基于快速连续的加压循环，测试了一种从沉积物中提取污染物的新方法，该方法包括将气体压缩到与沉积物接触的萃取溶剂中，然后立即通过排气减压。该技术提高了提取量并缩短了制备时间。测试了来自美国各地的PCB和PAH污染的沉积物样本，包括Passaic河，St。Louis河，Waukegan港和Wells国家河口研究保护区。将结果与索氏提取法进行比较。具体而言，在室温下，使用10个快速连续的压力循环（在压缩过程中N_2达到1.0 MPa）在10分钟内用50 mL己烷-丙酮（1：1）混合物在室温下提取15 g沉淀物。与索氏提取相比，使用新技术可以从沉积物中提取出更多的PAHs和PCBs。根据关键因素对萃取进行评估，这些关键因素包括压缩-减压循环次数，压缩压力，样品量，水分和加压气体类型。萃取性能的提高是通过重复压缩和减压步骤中气体溶解度的周期性变化来解释的，这引入了使沉积物聚集体碎裂的机制，从而增加了污染物的暴露和萃取。

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