Application of Cold-Induced Aggregation Microextraction Based on Ionic Liquid for Determination of Trace Amount of Cadmium and Lead in Powder Milk Samples

Background: cold-induced aggregation micro extraction based (CIAME) based on ionic liquid was used as a rapid and simple method for determination trace amounts of cadmium and lead in milk powder by analysis with flame atomic absorption spectrometry (FAAS). Methods: Sample solution containing of Cd2+ and Pb2+ in dynamic range, phosphate buffer (pH = 9, 3 ml), diethyl dithiocarbamate (complexing agent), Triton X-100, NaPF6 ,[HMIM][PF6] (extraction solvent) were transferred into conical bottom glass tube. Sample was kept in a thermostated bath and then ice bath; a cloudy solution was formed. Two phases separated by centrifugation. After removing of aqueous phase, IL-phase was dissolved in methanol and diluted was injected to the FAAS by microsampler introduction. Results: ILs, containing imidazoliumcation and hexafluoro phosphate anion, [HMIM][PF6](70mg), 200 mg NaPF6 ,0.01 mol.L-1 DDTC, 0.015% of Triton X-100 obtained, pH 9 and centrifuge time; 5 min (4000 rmp) was chosen. Detection limit were obtained 0.12 µgL-1, 1.61µgL-1, RSD 0.95%, 2.2% and enrichment factor of 70, 67 for Cd and Pb, respectively. Conclusion: CIAME allows determination of cadmium and lead in real samples in a simple, rapid and safe method with only a small amount of ionic liquid was used. In comparison with the organic solvent extraction, CIAME is much safer and the determination of species in high ionic strength samples is possible.