Dispersive magnetic solid phase extraction based on an ionic liquid ferrofluid

Abstract

A novel, fast and efficient ionic liquid-based dispersive magnetic solid phase extraction (IL-D-SPE) method was developed and applied for preconcentration of Cd(II) (as a model analyte) from aqueous solutions as a prior step to its determination by flame atomic absorption spectrometry (FAAS). In this methodology, after preparation of an appropriate ferrofluid, containing magnetic sorbent and an ionic liquid carrier, it was simply injected into the sample test tube. Afterwards, by reversing the tube, the extractant was wholly dispersed through the sample solution. As a result, a semi-opaque status was formed and the hydrophobic complex of the analyte was adsorbed/extracted by magnetic sorbent particles. By applying a magnetic field the particles were settled and the aqueous phase was simply removed by reversing. Finally, the sorbent was eluted and the concentration of the analyte was determined by FAAS. Compared to other magnetic solid phase extraction methods, handling and performance of this method are more facile as well as the extraction procedure being really short. In addition, this method is very useful and applicable for opaque/dark samples, in which observation and separation of the extraction phase are difficult. The applicability of the technique was evaluated by determination of trace amounts of cadmium in several water and milk samples. Under the optimum conditions, relative standard deviation (for 10 ng mL⁻¹ of cadmium) and the limit of detection were 4.0% and 0.11 ng mL⁻¹, respectively (n = 7). A maximum concentration factor of 200 was obtained, while the extraction time was less than five minutes.