Dispersive liquid-liquid microextraction based on solidification of floating organic drop for separation and preconcentration of malachite green before its determination by flow injection spectrophotometry

A simple and fast dispersive liquid-liquid microextraction based on solidification of floating organic drop has been developed for the separation and preconcentration of malachite green in water samples prior to its determination by flow injection spectrophotometry. Sodium lauryl sulfate, an anionic surfactant, was used for the ion-pair formation with malachite green. The factors affecting the ion-pair formation and extraction were optimized. Under the optimized conditions (volume of 1-undecanol as the extraction solvent, 40 mu L; the volume of ethanol as the disperser solvent, 100 mu L; sodium lauryl sulfate concentration, 7.5 x 10(-7) mol L-1, and the pH of the sample, similar to 3.0), the calibration graph was linear over the range of 0.8-25 mu g L-1 with the detection limit of 0.3 mu g L-1 and the preconcentration factor of 750. The relative standard deviation at 7 mu g L-1 (n = 6) was found to be 2.1%. The developed method was successfully applied to the determination of malachite green in river water and fish farming water samples.