Comparative study techniques for TPH and PAH extraction from clayey and sandy soils for chromatography analyses

Abstract

The objective of this study was to compare three extraction procedures: soxhlet (SOX), microwaves (MARS) and accelerate extraction with solvent (ASE) regarding the extraction efficiency of different fractions of total petroleum hydrocarbons (TPH) and polycyclic aromatic hydrocarbons (PAH) from sandy and clayey soil with aged contamination analyzed by gas chromatography. Besides the extraction efficiency, water, solvent and time consumption were considered. Regarding clayey soil, for the extraction of different fractions of total petroleum hydrocarbons (TPH), ASE resulted in better recovery of n-alkanes and hydrocarbons resolved fraction (HRF). SOX and MARS performed better for the heaviest fraction (non-resolved complex mixture-NRCM). Regarding sandy soil, ASE performed better during extraction of all TPH fractions. In the case of polycyclic aromatic hydrocarbons (PAH), extraction with ASE showed the best result in both clayey and sandy soils. When other variables were taken into account (water, solvent and time consumption), MARS is the most economical method, particularly when TPH is the group of interest and n-alkanes is relatively less important in the analysis. Therefore, in aged contaminations, soil texture and the petroleum fraction of interest in the first place and availability of resources such as water, solvent and time in the second place must be considered before deciding what is the most appropriate extraction method.