Capabilities and limitations of dispersive liquid–liquid microextraction with solidification of floating organic drop for the extraction of organic pollutants from water samples

• Extraction efficiency of DLLME-SFO was determined for 29 organic pollutants.
• Pollutants with Log Kow 3–7 had similar and satisfactory recoveries (%R > 70).
• For those compounds, %R was independent of chemical nature or hydrophobicity.
• Solutes with Log Kow 1.5–2.8 had %R 13–62, preserving good linearity and precision.
• Log Kow value showed suitable for estimating extraction recovery in DLLME-SFO.

Dispersive liquid–liquid microextraction with solidification of floating organic drop (DLLME-SFO) is one of the most interesting sample preparation techniques developed in recent years. Although several applications have been reported, the potentiality and limitations of this simple and rapid extraction technique have not been made sufficiently explicit. In this work, the extraction efficiency of DLLME-SFO for pollutants from different chemical families was determined. Studied compounds include: 10 polycyclic aromatic hydrocarbons, 5 pesticides (chlorophenoxy herbicides and DDT), 8 phenols and 6 sulfonamides, thus, covering a large range of polarity and hydrophobicity (Log Kow 0–7, overall). After optimization of extraction conditions using 1-dodecanol as extractant, the procedure was applied for extraction of each family from 10-mL spiked water samples, only adjusting sample pH as required. Absolute recoveries for pollutants with Log Kow 3–7 were >70% and recovery values within this group (18 compounds) were independent of structure or hydrophobicity; the precision of recovery was very acceptable (RSD < 12%) and linear behavior was observed in the studied concentration range (r2 > 0.995). Extraction recoveries for pollutants with Log Kow 1.46–2.8 were in the range 13–62%, directly depending on individual Log Kow values; however, good linearity (r2 > 0.993) and precision (RSD < 6.5%) were also demonstrated for these polar solutes, despite recovery level. DLLME-SFO with 1-dodecanol completely failed for extraction of compounds with Log Kow ≤ 1 (sulfa drugs), other more polar extraction solvents (ionic liquids) should be explored for highly hydrophilic pollutants.

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