Selective dispersive liquid–liquid microextraction and preconcentration of Ni(II) into a micro droplet followed by ETAAS determination using a yellow Schiff's base bisazanyl derivative

A simple, rapid and sensitive method was developed for the selective separation and preconcentration of Ni(II) using dispersive liquid–liquid microextraction, by a yellow Schiff's base bisazanyl derivative, as a selective complexing agent. In this method, a mixture of 45 μL chloroform (extraction solvent) and 450 μL tetrahydrofuran (dispersive solvent) is rapidly injected by syringe into a 5 mL aqueous sample containing 3% (w/v) sodium chloride and an appropriate amount of the Schiff's base. As a result, a cloudy solution is formed by entire dispersion of the extraction solvent into the aqueous phase. After centrifuging for 5 min at 5000 rpm, the sedimented phase is directly injected into the electrothermal atomic absorption spectrometry for Ni(II) determination. Some important parameters, such as kind and volume of extraction and dispersive solvents, extraction time, salt effect, pH and concentration of the chelating agent have been optimized. Under the optimum conditions, the enrichment factor for the presented method is 138. The calibration curve was linear over a nickel concentration range of 10–50 ng mL− 1. The detection limit and relative standard deviation were 0.04 ng mL− 1 and 2.1%, respectively. The method was successfully applied to the extraction and determination of Ni(II) in different water samples.

► A new synthesized schiff's base was used for selective separation of Ni(II) ions.
► The method based on DLLME was successfully applied to the determination of Ni(II).
► A cloudy solution is formed by entire dispersion of the extraction solvent into the aqueous phase.
► In this work, the response surface analysis was used for the optimization purpose.
► The curvature of response surface reflects the interactive effect of the variables.