Sugar based natural deep eutectic solvent liquid liquid microextraction for the determination of nickel and copper in...

A new method combining liquid-liquid microextraction (LLME) with flame atomic absorption spectroscopy (FAAS) is presented for the accurate determination of Ni(II) and Cu(II) ions. The extraction efficiency of five distinct natural deep eutectic solvents (NADES) composed of sugar molecules (abbreviated as SDES) was evaluated. The SDESs tested consist of the components betaine, fructose, glucose, sucrose, maltose, lactose, and L-proline. In order to facilitate the extraction of Ni (II) and Cu (II) ions into the SDES phase, these ions were complexed with cyclam (prepared at a concentration of 1.0 × 10^- 3 mmol L^- 1). Optimization of important parameters of the developed method was performed using statistical and mathematical optimization technique. This approach promises a more minimal method owing to Central Composite Design (CCD) used. In parallel, it contributes to the efficiency of the analytical parameters and the greenness of the procedure. The method based on ultrasound-assisted liquid-liquid microextraction using a natural deep eutectic solvent with a sugar component (UA-SDES-LLME) has the characteristics of being simple, low-cost, green and applicable. The developed method provided high accuracy (recoveries of 97.8% and 96.5% for Ni (II) and Cu (II), respectively), high precision (relative standart deviations (RSDs) of 2.3% and 2.0%, respectively), high sensitivity (limits of determination (LODs) of 0.33 and 0.15 µg L^- 1, respectively) and a satisfactory preconcentration factor (PF, 96) under optimum conditions. The UA-SDES-LLME method developed has been applied to various tea and environmental water samples.