Speciation, separation and enrichment of Cr(III) and Cr(VI) in environmental samples by ion-pair solvent extraction using a beta-diketone ligand

A simple speciation, separation and enrichment method has been developed for the determination of Cr(III) and Cr(VI) ions in different samples by ion-pair solvent extraction with a beta-diketone ligand, 2-(4-methoxybenzoyl)-N'-benzylidene-3-(4-methoxyphenyl)-3-oxo-N-phenyl-propono hydrazide (MBMP). Cr(III) was separated from Cr(VI) as Cr(III)-(MBMP)-perchlorate ternary ion-pair complex. The influences of various analytical parameters including pH, amount of reagent, shaking time, sample volume and ionic strength on the recovery of Cr(III) and/or Cr(VI) were investigated. Total chromium was obtained after reducing Cr(VI) to Cr(III) with NH(2)OH center dot HCl. Recoveries were found to be higher than 95% and the relative standard deviation (RSD) was less than 2%. The method detection limit based on 3 sigma criterion for Cr(III) was found to be 0.32 mu g L(-1). The formed ternary ion-pair complex, Cr(III) : MBMP: 2ClO(4), has a molar ratio of 1 : 1 : 2. The developed method has been applied successfully to the speciation of chromium in various natural water, soil, sediment and hair samples with satisfactory results.A simple speciation, separation and enrichment method has been developedfor the determination of Cr(III) and Cr(VI) ions in different samples byion-pair solvent extraction with a -diketone ligand, 2-(4-methoxybenzoyl)-N0-benzylidene-3-(4-methoxyphenyl)-3-oxo-N-phenyl-propono hydrazide (MBMP).Cr(III) was separated from Cr(VI) as Cr(III)-(MBMP)-perchlorate ternaryion-pair complex. The influences of various analytical parameters including pH,amount of reagent, shaking time, sample volume and ionic strength on therecovery of Cr(III) and/or Cr(VI) were investigated. Total chromium wasobtained after reducing Cr(VI) to Cr(III) with NH2OH HCl. Recoveries werefound to be higher than 95% and the relative standard deviation (RSD) was lessthan 2%. The method detection limit based on 3 criterion for Cr(III) was foundto be 0.32 mg L-1. The formed ternary ion-pair complex, Cr(III) :MBMP: 2ClO4,has a molar ratio of 1 : 1 : 2. The developed method has been applied successfullyto the speciation of chromium in various natural water, soil, sediment and hairsamples with satisfactory results.