A dispersive liquid-liquid microextraction procedure for UV-Vis spectrophotometric determination of chromium(VI) in water samples

A novel and simple procedure for chromium determination has been developed. The method is based on the reaction of chromium(VI) with dimethylindocarbocyanine dye reagent (DIC) in an acidic medium and in the presence of chloride ions, followed by dispersive liquid-liquid microextraction of the formed ion associate into the organic phase containing a mixture of toluene (extraction solvent), carbon tetrachloride (auxiliary solvent) and acetonitrile (dispersive solvent) in a ratio of 1 : 1 : 2 (v : v : v) and subsequent UV-VIS detection at 550 nm. The calibration plot was linear in the range 0.10-0.52 mg L-1 of chromium. The limit of detection calculated based on 3s and limit of quantification calculated based on 10s is 0.03 mg L-1 and 0.07 mg L-1. The method was applied to the determination of chromium(VI) in spiked water samples.