Development of air assisted liquid phase microextraction based on switchable-hydrophilicity solvent for the determination of palladium in environmental samples

• A switchable solvent with air-assisted liquid–liquid microextraction has been applied.
• A stable homogeneous SHS/water mixture is provided by using dry ice as a reagent.
• The reaction between hydrated CO2 and the switchable solvent changes the miscibility.
• AALLME leads to the rapid formation of fine droplets of the extractant.

A novel switchable-hydrophilicity solvent (SHS) in combination with air-assisted liquid–liquid microextraction (AALLME) which called AA-SHS-LPME, has been applied for preconcentration of Pd(II). A water-immiscible solvent, Triethylamine (TEA), was used as a green switchable solvent that switched reversibly between one form that was miscible with water to another that formed a biphasic mixture with water. CO2 was used as a stimulus for triggering the transformation to the water-miscible form and removal of CO2 to achieve the reverse. Separation was carried out by addition of sodium hydroxide, which produced a change on the ionization state of amine. AALLME led to the rapid formation of fine droplets of the extractant in the aqueous solution, and the contact surface between both immiscible liquids was significantly enlarged. Detection limit value, preconcentration factor and relative standard deviation (RSD, n=10) were found 0.07 μg L−1, 64 and 3.5% respectively. The recovery of the analyte in water, road dust and catalytic converter samples was in the range of 98.3–103.2%. The obtained results indicated that the developed method could be an efficient analytical method for the routine analysis in the environmental field.

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