A two‐step supercritical fluid extraction of polycyclic aromatic hydrocarbons from roadside soil samples

Abstract

A two-step procedure for the supercritical fluid extraction (SFE) of polycyclic aromatic hydrocarbons from soil samples was developed. The procedure consists of a static supercritical fluid treatment in a closed extraction cell at a high temperature (T=250 or 340degreesC for 20 min) and an SFE with a solvent trapping. During the static phase, the sample is exposed to a supercritical organic solvent (methanol, toluene, dichloromethane, ACN, acetone, and hexane). The solvent penetrates particles of the matrix to substitute strongly bonded molecules and dissolves the analytes in the supercritical phase. At ambient temperature, supercritical fluids became liquid and lost their solvation abilities. Most of the analytes condense on the surface of the particles or on the extraction cell walls without forming strong bonds or penetrating deep into the matrix. Thus, the pretreatment liberates the analytes and they behave similar to those in freshly spiked samples. The common SFE with toluene-modified CO2 as an extraction fluid follows the static phase. With the use of the most suitable extraction phases (toluene, ACN), the extraction efficiency of the combined procedure is much higher (approximately100%). The results of the combined procedure are compared to the SFE procedure of the same untreated sample (difference less than 5%) and to the Soxhlet extraction. The extracts were analyzed using a GC with the flame ionization detection.

Decontamination of hazardous substances from solid matrices and liquids using supercritical fluids extraction: A review

“…The addition of co-solvents and surfactant to supercritical CO 2 can boost its extraction efficiency, especially for several hazardous organic compounds [22][23][24][25][26][27][28][29][30][31][32][33][34][35]. Incorporation of slight amounts of a hydrogen bond acceptor or Lewis base co-solvent compounds leads to high solubility amplification, as it reinforces solute-solvent interaction by means of: (1) incrementing density, (2) promoting certain chemical interactions, e.g.…”

“…The dipole moment, Bronsted acidity or basicity of these co-solvents also play substantial role in disrupting hazardous compounds-soil matrix interactions [31]. Lojkova et al [35] resorted to two-step procedure for the SFE of PAHs from soil samples. Their procedure includes a static supercritical fluid treatment as the first step followed by SFE with solvent trapping as the second step.…”

“…Once entering the soil matrices, due to their low solubility and vapor pressure which is even lowered for higher molecular weight compounds, PAHs would then be adsorbed on soil and deposited in the matrices. Several studies on the detachment of these compounds from soil exploiting SFE technology have been conducted by numerous researchers [22,[30][31][32]34,35,.…”

“…The selection of operating parameters (pressure and temperature) depends on the specific compounds to [35] be extracted. Pressure is the most relevant process parameter to control the solvating power and extraction efficiency.…”

Supercritical Fluid Extraction of Microcystin LR from Cyanobacteria using Aqueous Acetonitrile Modifier

“…[17] Other applications have been described in many articles. [18,19] This study describes an investigation conducted to evaluate the applicability and efficiency of SFE methods for the extraction of blue-green algal hepatotoxin, microcystin LR from cyanobacteria.…”