Experimental Design Optimization of Supramolecular Dispersive Liquid–Liquid Microextraction of Nickel and its Spectrophotometric Determination

A supramolecular dispersive liquid−liquid microextraction method based on the solidification of the floating organic drop (SM-DLLME-SFOD) combined with spectrophotometry was developed for the separation, preconcentration, and determination of trace amounts of nickel from aqueous samples. The method is based on the extraction of the hydrophobic complex of nickel with α-furildioxime in the coacervates made up of undecanol reverse micelles in a water-tetrahydrofuran mixture. The parameters affecting the extraction of nickel were screened by fractional factorial design with central points. Effective experimental parameters were optimized using central composite design. Under the optimized conditions, the calibration graph was linear for nickel in the concentration range of 3–85 µg/L with a determination coefficient of 0.9992. The limit of detection and the enhancement factor of the method were 0.4 µg/L and 147, respectively. The method was successfully applied to the determination of nickel in water and vegetable samples.