Study of the microwave-assisted extraction technique for its application to the determination of total petroleum hydrocarbons in soils

This research develops an efficient analytical method for the extraction of TotalPetroleum Hydrocarbons (TPH’s) in soils using Microwave-Assisted Extraction(MAE) and performing the quantification by infrared spectroscopy. The researchrecalls the importance of the extraction step within the analytical procedure forthe analysis of TPH’s. Different extraction conditions in the microwave-assistedextraction system were evaluated to optimize the analytical technique. The mid-dle section of this work presents the main results obtained and noted the finalextraction conditions: amount of sample 2 g; solvent volume 10 mL; extractiontemperature 40 °C; extraction time 10 minutes and amount of silica to removeinterferences 1 g. To satisfy the analytical method requirement, some validationparameters were evaluated enabling the proposed procedure to be executed,the following results are shown: linearity of the calibration curves R2< 0.99;working range 100-7500 mg/kg; limit of detection 25 mg/kg; limit of quantifi-cation 100 mg/kg; repeatability C.V. < 10% and reproducibility precision C.V.< 10%. One additional analysis which involved a certified reference materialwas performed by microwave-assisted extraction and a conventional techniqueto make an accuracy comparison. Finally, advantages of the proposed methodare discussed.