Development of green miniaturized dispersive ionic liquid nano-emulsion method for preconcentration of cadmium from canal and waste water samples prior to coupling with graphite furnace atomic absorption spectrometry

Abstract

A green miniaturized dispersive ionic liquid nano-emulsion extraction (NDILE) method has been developed for the preconcentration of trace levels of cadmium (Cd) in canal, tap and waste water samples. In the proposed approach, 1-butyl-3-methylimidazolium hexafluorophosphate, [C₄mim][PF₆], was dispersed into nano-emulsions by a low-energy emulsification phase inversion method, stabilized by a nonionic surfactant (TX-114). The influence of variables such as ionic liquid volume, concentration of the surfactant, stirring rate and time was studied and optimized. The morphology of the nano-emulsion system and its stability were evaluated through visual assessment and optical light microscopy. Ionic liquid nano-emulsion (ILN) was used as a dispersive and extractive medium, due to its small size and high surface area, to enhance the extraction efficiency of Cd complexed with 8-hydroxyquinoline from aqueous media. Separation of stable ILN could be induced by the micellar cloud point extraction approach. Under optimum conditions, the limit of detection and enhancement factor were found to be 0.48 ng L⁻¹ and 180, respectively. Validation of the developed method was carried out by Cd determination using a certified reference material (SLRS-4 Riverine water) and the results were found to be in good agreement with the certified values. The proposed novel method was successfully applied for determination of Cd in real water samples.