Determination of Cr(VI) in potable water samples after selective preconcentration on oxalate form of Dowex-1 and electro thermal atomic absorption spectrometric determination

A method for preconcentration of Cr(VI) from potable water samples was developed using oxalate form of Dowex-1. The resin was found to adsorb Cr(VI) selectively in presence of Cr(III). The percentage recovery (adsorption and elution) of Cr(VI) from water samples was 98.0 ± 1.0. The leaching of adsorbed Cr due to the reduction of Cr(VI) to Cr(III) reported earlier, on chloride form of Dowex-1, as a result of oxidation property of Cr(VI) on organic resins has not been observed. The method has been applied for the separation and preconcentration of Cr(VI) from Cr(III) in potable water samples. The adsorbed Cr(VI) was eluted using 0.8 M HNO3. The measurements were carried out using ET-AAS. The method has been applied for the determination of Cr(VI) in two synthetic water samples, and four real samples. The R.S.D. of the procedure was ∼3% at 10 ng mL−1 and ∼25% at 0.3 ng mL−1. The limit of detection of the method was 0.027 ng mL−1 based on signal corresponding to 0.0044 AU with a 25-fold preconcentration.