Synthesis of a New α-Dioxime Derivative and Its Application for Selective Homogeneous Liquid-Liquid Extraction of Cu(II) into a Microdroplet Followed by Direct GFAAS Determination

A fast and reliable method for the selective separation and preconcentration of Cu²⁺ ions using homogeneous liquid-liquid extraction was developed. A new α-dioxime derivative (2H-1,4-benzothioazine-2,3(4H)dionedioxime, Dioxime I) was synthesized and investigated as a suitable selective complexing ligand for Cu²⁺ ions. Zonyl FSA (FSA) was applied as a phase-separator agent under the slightly acidic pH conditions. Under the optimal experimental conditions ([FSA] = 3.2% w/v, [THF] = 19.5% v/v, [Dioxime I] = 1.9 x 10.3 M, and pH = 4.7), 10 μg of Cu²⁺ in 5.2 mL aqueous phase could be extracted quantitatively into 80 μL of the sedimented phase. The maximum concentration factor was 65-fold. The limit of detection of the proposed method was 0.005 ng mL.1. The reproducibility of the proposed method, on the 10 replicate measurements, was 1.3%. The influence of the pH, type and volume of the water-miscible organic solvent, concentration of FSA, concentration of the complexing ligand and the effect of different diverse ions on the extraction and determination of Cu²⁺ ions were investigated. The proposed method was applied to the extraction and determination of Cu²⁺ ion in different synthetic and natural water samples