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Determination of iron, manganese and zinc in water samples by flame atomic absorption spectrophotometry after preconcentration with solid-phase extraction onto Ambersorb 572.

A solid-phase extraction method for the preconcentration of Fe, Mn and Zn on a column containing Ambersorb 572 has been developed, and the determination of Fe, Mn and Zn in water using a flame atomic absorption spectrophotometer (FAAS) has been performed. The optimum preconcentration parameters of the procedure have been determined. The effect of the pH, complexing agent, amount of adsorbent, flow rate, concentration and volume of the elution solution and interfering ions on the recovery of the analytes were investigated. The recoveries of Fe, Mn and Zn were 99 +/- 3%, 98 +/- 3% and 99 +/- 3% at the 95% confidence level, respectively, under the optimum conditions. Fe, Mn and Zn were preconcentrated up to 50, 100, 200, respectively. The limits of detection of Fe, Mn and Zn are 2.5, 0.68 and 0.24 micrograms l-1, respectively. The adsorption capacity of the adsorbent was found to be 10.9, 13.1 and 21.5 mg g-1 for Fe, Mn and Zn, respectively. The method has been applied to the determination of these metal ions in tap-water and river-water samples. The precision and the accuracy of the method is very good. The relative standard deviation and the relative error are lower than 4%.