Spectrophotometric determination of mercury using vortex-assisted liquid--liquid microextraction

A novel method for the determination of mercury(II) is suggested. The procedure is based on the formation of an ion associate between the bromide complex of Hg(II) and Astrazon Red 6B dye and vortex-assisted liquid-liquid microextraction of the ion associate formed, with subsequent spectrophotometric detection. The variables that affect the procedure, such as pH, the concentration of ligand and dye, the type and volume of extraction solvent, and the rate and time of vortex mixing, were optimized. Under optimum conditions (pH 2.0, 0.01 mol L$^{-1}$ KBr, 2 $\times $ 10$^{-4}$ mol L$^{-1}$ AR6B, 50 $\mu $L of the extraction mixture toluene:dichlorethane, 4:1, v:v, vortex mixing for 100 s~at 1600 rpm) the linear range was 8 to 200 $\mu $g L$^{-1}$ Hg(II), with the limit of detection at 1.5 $\mu $g L$^{-1}$. The method was applied to the determination of mercury in water samples.