%0 Journal Article
%T Extraction Techniques for Polycyclic Aromatic Hydrocarbons in Soils
%A E. V. Lau
%A S. Gan
%A H. K. Ng
%J International Journal of Analytical Chemistry
%D 2010
%I Hindawi Publishing Corporation
%R 10.1155/2010/398381
%X This paper aims to provide a review of the analytical extraction techniques for polycyclic aromatic hydrocarbons (PAHs) in soils. The extraction technologies described here include Soxhlet extraction, ultrasonic and mechanical agitation, accelerated solvent extraction, supercritical and subcritical fluid extraction, microwave-assisted extraction, solid phase extraction and microextraction, thermal desorption and flash pyrolysis, as well as fluidised-bed extraction. The influencing factors in the extraction of PAHs from soil such as temperature, type of solvent, soil moisture, and other soil characteristics are also discussed. The paper concludes with a review of the models used to describe the kinetics of PAH desorption from soils during solvent extraction. 1. Introduction Polycyclic aromatic hydrocarbons or polynuclear aromatic hydrocarbons (PAHs) are compounds produced through incomplete combustion and pyrolysis of organic matter. Both natural and anthropogenic sources such as forest fires, volcanic eruptions, vehicular emissions, residential wood burning, petroleum catalytic cracking, and industrial combustion of fossil fuels contribute to the release of PAHs to the environment [1]. The presence of PAH compounds in soils is an issue of concern due to their carcinogenic, mutagenic, and teratogenic properties. In 2008, 28 PAHs have been identified as priority pollutants by the National Waste Minimization Programme, a project which is funded by US Environment Protection Agency [2]. PAHs which consist of fused benzene rings are hydrophobic in nature with very low water solubility and high octanol-water partition coefficient ( ). Hence, they tend to adsorb tightly to organic matter in soil rendering them less susceptible to biological and chemical degradation. Prolonged aging time in contaminated soil promotes the sequestration of PAH molecules into micropores and increases the recalcitrance of PAHs towards treatment [3]. Thus the extraction process of PAHs from soil for analysis is made more complicated due to these factors. In this paper, various analytical extraction techniques for PAHs in soils will be reviewed, ranging from more widely applied methods such as Soxhlet extraction, sonication, mechanical agitation, and accelerated solvent extraction to alternative ones such as supercritical and subcritical fluid extraction, microwave-assisted extraction, solid phase extraction and microextraction, thermal desorption and flash pyrolysis, as well as fluidised-bed extraction. The influencing factors in the extraction of PAHs from soil such as temperature,
%U http://www.hindawi.com/journals/ijac/2010/398381/