Sequential accelerated solvent extraction of polycyclic aromatic hydrocarbons with different solvents: performance...

Area of Science:

• Environmental Chemistry
• Organic Geochemistry

Background:

• Polycyclic Aromatic Hydrocarbons (PAHs) are persistent organic pollutants originating from petrogenic and pyrogenic sources.
• Understanding PAH extraction efficiency and sources is crucial for environmental risk assessment.

Purpose of the Study:

• To compare the efficiency of Soxhlet extraction (S-PAHs) and accelerated solvent extraction (A-PAHs) for sixteen USEPA priority PAHs.
• To investigate the impact of different organic solvents and sequential extraction on PAH recovery.
• To determine the sources of PAHs in soil, sediment, and oil shale samples from the Pearl River Delta.

Main Methods:

• Soxhlet extraction with dichloromethane.
• Accelerated Solvent Extraction (ASE) with toluene/methanol and four different organic solvents.
• Analysis of sixteen USEPA priority PAHs in 24 soil samples, sediments, and oil shale.
• Diagnostic ratio analysis and correlation with organic carbon content.

Main Results:

• ASE yielded 2.41 times higher PAH concentrations than Soxhlet extraction.
• Toluene showed the best extraction performance in sequential ASE.
• PAH diagnostic ratios indicated similar petrogenic and pyrogenic sources in soils/sediments, but a petrogenic origin in shale.
• Perylene/5-ring PAH ratios suggested a diagenetic source, particularly in shale and sediments.
• PAH extraction efficiency correlated better with total organic carbon (TOC) than black carbon (BC).

Conclusions:

• ASE is a more efficient method for extracting PAHs from environmental samples compared to Soxhlet extraction.
• The primary source of PAHs in the studied soils and sediments is petrogenic.
• Organic matter content plays a significant role in the extraction and distribution of PAHs.