Salting-Out Assisted Liquid-Liquid Extraction of Cr (VI) from Water Samples before Its Determination by UV-Vis Spectrophotometry

This paper proposes salting-out assisted liquid-liquid extraction for selective extraction of a Cr (VI)-1,5-diphenylcarbazide complex before its determination by UV-Vis spectrophotometry. Parameters affecting the complexation process and the extraction efficiency of the method were studied. The highest extraction efficiency was obtained when acetonitrile was used as an extraction solvent and (NH4)(2)SO4 was used as a salting-out agent. Under optimum conditions, the calibration curve constructed at seven concentration points exhibited good linearity from 0.015 to 2.00 mg/L with a 0.9973 coefficient of determination. The method's detection and quantification limits were 0.004 and 0.015 mg/L, respectively. The method showed a 5.8 enrichment factor. The intra- and inter-day precisions studied at two concentration levels (0.75 and 1.25 mg/L) showed relative standard deviation values of <9.0. The recoveries of the spiked water samples at the two concentration levels ranged from 88.0 +/- 2.5 to 97.3 +/- 0.1%. The method demonstrated negligible interferences (<5%) for Fe, Cu, V, and Cd up to 500 mg/L. The findings showed that the method is simple, rapid, efficient, and selective to be used as an alternative procedure for analyzing Cr (VI) from water and other related matrices.