A successive homogeneous liquid-liquid microextraction based on solidification of switchable hydrophilicity solvents and ionic liquids for the detection of pyrethroids and cadmium in drinks

A simple, efficient, and environmentally friendly method for the determination of pyrethroids and cadmium in drink samples was developed by successive homogeneous liquid-liquid microextraction (SHLLME) based on switchable hydrophilicity solvents and ionic liquids coupled with high-performance liquid chromatography-diode array detector (HPLC-DAD) and graphite furnace atomic absorption spectrometry (GFAAS) detection. The extraction of pyrethroids needs to be conducted under acidic conditions, while cadmium needs to be extracted under neutral or slightly alkaline conditions. In SHLLME, hydrophobic fatty acids and ionic liquids were generated in situ as extraction solvents for pyrethroids and cadmium, respectively. Acidic ionic liquids and sodium carbonate were successively applied to adjust the pH value of the sample solution. The SHLLME procedure was optimized by univariate analysis and the Box-Behnken response surface methodology . Optimum conditions were as follows: 105 mg of sodium decanoate , 246 mg of [Emim][HSO 4 ], 131 mg of sodium fluoroborate amount, and 128 mg of sodium carbonate. Under optimized conditions, the extraction recovery varied from 77.0% to 97.2%, and relative standard deviations varied from 0.5% to 4.5%. The limits of detection were 0.6 μg L −1 and 0.006 μg L −1 for pyrethroids and cadmium, respectively. This established method has the potential to continuously extract compounds with different physical and chemical properties.