**4.4 Effect of the amount of the complexing agent**

The effects of the amounts of complexing agent on the adsorption of analytes keeping other parameters constant are investigated. For this purpose, the prepared model samples are generally passed through the column containing 1.0, 1.5, 2.0, 3.0 and 4.0 g of the complexing agent. The retained analytes on the complexing agent are usually eluted 10 mL of 1 mol L<sup>−</sup><sup>1</sup> HNO3.
