Coupled Subcritical Water Extraction with Solid-Phase Microextraction for Determining Semivolatile Organics in Environmental Solids

Abstract

Efficient extractions of semivolatile organic pollutants from solid samples can be obtained using subcritical (hot/liquid) water by simply placing the sample in an extraction cell, filling the cell with water, and heating the system in an oven. After a 15−60-min extraction, the cell is cooled, the water is removed from the extraction cell, and the solubilized organics are analyzed using solid-phase microextraction (SPME). Quantitative determinations (recoveries typically ranging from ∼60 to 140% compared to conventional solvent extraction) of polycyclic aromatic hydrocarbons (PAHs) from soil and air particulate matter were achieved using a 250 °C extraction step and isotopically labeled PAHs as internal standards. Quantitative determinations of more volatile (e.g., alkylbenzenes) and more polar compounds (e.g., aromatic amines) from contaminated soil using external standards of pure target analytes also showed good general agreement with conventional solvent extraction. Relative standard deviations (RSDs) of replicate water extraction/SPME determinations compared favorably with those of conventional liquid solvent techniques (e.g., RSDs typically ranged from 2 to 33%). The method is simple to perform, uses very inexpensive apparatus, and utilizes no organic solvents.