Study on Extraction Efficiency of Polycyclic Aromatic Hydrocarbons (PAHs) in Soil Samples by Ultrasonic Methods
Main Article Content
Abstract
Polycyclic aromatic hydrocarbons (PAHs) are a typical group of organic pollutants and are commonly found in the soil environment. Analytical procedures for PAHs in soil samples typically consist of three main steps: sample extraction, extract clean up, and enrichment concentration prior to quantitative analysis. Ultrasonic extraction is a technique with several advantages such as simple, fast, effective, and chemical saving. In this study, the efficiency of PAHs extraction from soil samples was investigated using direct extraction (with a focused ultrasonic processor) and indirect extraction (with an ultrasonic bath) techniques with 3 different solvent systems such as acetone, dichloromethane, and acetone/hexane (1:1, v/v). The extract was purified on a glass column containing activated silica gel and anhydrous sodium sulfate with dichloromethane/hexane (1:3, v/v) as elution solvent. Concentrations of 18 PAHs in soil samples were determined by gas chromatography/mass spectrometry (GC/MS). Method detection limits of PAHs ranged from 0.20 to 3.0 ng/g. Total concentrations of 18 PAHs (Σ18PAHs) in the studied soil samples ranged from 30.8 to 55.7 ng/g and the benzo[a]pyrene equivalent (BaP-EQ) values ranged from 6.3 to 9.4 ng BaP-EQ/g. Based on Σ18PAHs and BaP-EQ values, soil extraction using ultrasonic bath with acetone provided the highest extraction efficiency. This sample extraction condition can be applied for further studies to assess the pollution levels and impacts on environmental and human health of PAHs in soil.
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