preconcentration and speciation of chromium using dispersive liquid-liquid microextraction; application to milk and different water samples

a simple and rapid microextraction procedure based on dispersive liquid-liquid microextraction (dllme) was developed for determination and speciation of trace amounts of chromium (cr) by flame atomic absorption spectrometry (faas). in the proposed approach, chloroform and methanol were used as extraction and dispersive solvents. a new schiff's base ligand, bis(2-methoxy benzaldehyde) ethylene diimine was used as complexing agent. effect of extraction solvent, disperser solvent, the volume of extraction and disperser solvent, ph of the aqueous solution and extraction time on extraction procedure were investigated and optimized. under the optimum conditions, the calibration graph was linear in the range of 1-50 µg l-1 with a limit of detection of 0.7 µg l-1. the relative standard deviation (rsd%) was 2.7% (n = 7) for cr(iii). the relative recoveries of spiked samples were between 98% and 102% and preconcentration factor (pf) was 20. the proposed method is a simple, fast, accurate, highly stable and selective and was applied for determination of chromium in milk and water samples with satisfactory results.