Dispersive liquid-liquid microextraction (DLLME) was applied to the separation and preconcentration of Cd(II) and Co(II) from water and food samples. The influence of the following analytical parameters on the quantitative recoveries of cadmium and cobalt were investigated: pH, extraction solvent volume, dispersing solvent volume and type, and concentration of chelating agent. Under the optimized conditions, the detection limits were 2 μg L-1 and 13 μg L-1 for Cd(II) and Co(II), respectively. The proposed method was validated by the analysis of certified samples and has been applied to the determination of these ions in environmental water samples, with recoveries of 98 – 101% for Co(II) and 94 – 120% for Cd(II). In food samples the recoveries fell between 100 – 110% and 101-120% for Co(II) and Cd(II), respectively.
 Donati, G.L.; Nascentes, C.C.; Nogueira, A.R.A.; Arruda, M.A.Z.;
Nóbrega, J.A. Acid extraction and cloud point preconcentration
as sample preparation strategies for cobalt determination
in biological materials by thermospray flame furnace atomic
absorption spectrometry. Microchem. J., 2006, 82, 189-195.
 Cundeva, K.; Stafilov, T.; Pavlovska, G. Flotation separation of
cobalt and copper from fresh waters and their determination by
electrothermal atomic absorption spectrometry. Microchem. J.,
2000, 65, 165-175.
Financed by the National Centre for Research and Development under grant No. SP/I/1/77065/10 by the strategic scientific research and experimental development program:
SYNAT - “Interdisciplinary System for Interactive Scientific and Scientific-Technical Information”.