Serrano A, Gallego M
Department of Analytical Chemistry, Campus of Rabanales, University of Córdoba, E-14071 Córdoba, Spain.
J Chromatogr A. 2006 Jun 23;1118(2):261-70. doi: 10.1016/j.chroma.2006.03.095. Epub 2006 Apr 18.
A sorption study of 25 volatile organic compounds (VOCs) in different agricultural soils was carried out by using headspace-gas chromatography-mass spectrometry. The extraction of the VOCs from soil samples was carried out following the EPA method with some differences such as addition of potassium chloride and different instrumental conditions which provide higher sample throughput. In addition, a complementary study on several procedures for soil fortification with VOCs was also assayed, fortification with minimal sample handling was selected in order to minimise evaporation losses of the VOCs. The effect of clay minerals (7.0-69.7%) and organic carbon (0.2-3.5%) contents on acid and alkaline (pH 5.3-8.8) soils were evaluated. Based on the results, all compounds assayed were more sorbed in alkaline soils than acid ones; chlorobenzenes interact more strongly with agricultural soils than do alkylbenzenes. The organic carbon content affects the sorption of 25 VOCs in alkaline soils (the highest sorption was found for the most organic soil), while in acid soils VOC sorption increases as the organic carbon content decreases. The clay mineral fraction plays an important role in the sorption of VOCs in acid soil owing to pi-/n-electron interactions, this effect being more marked for chlorobenzenes.
采用顶空-气相色谱-质谱联用技术，对25种挥发性有机化合物（VOCs）在不同农业土壤中的吸附情况进行了研究。土壤样品中VOCs的提取按照美国环境保护局（EPA）的方法进行，但存在一些差异，如添加氯化钾以及采用不同的仪器条件，这些条件可提高样品通量。此外，还对几种VOCs土壤强化程序进行了补充研究，选择了样品处理最少的强化方法，以尽量减少VOCs的蒸发损失。评估了粘土矿物（7.0 - 69.7%）和有机碳（0.2 - 3.5%）含量对酸性和碱性（pH 5.3 - 8.8）土壤的影响。结果表明，所有被测化合物在碱性土壤中的吸附量均高于酸性土壤；氯苯与农业土壤的相互作用比烷基苯更强。有机碳含量影响25种VOCs在碱性土壤中的吸附（在有机含量最高的土壤中吸附量最大），而在酸性土壤中，VOCs的吸附量随有机碳含量的降低而增加。由于π-/n-电子相互作用，粘土矿物部分在酸性土壤中VOCs的吸附中起重要作用，这种作用对氯苯更为显著。
