Determination of Metals in Natural Waters by Inductively Coupled Plasma Optical Emission Spectroscopy after Preconcentration on Silica Sequentially Coated with Layers of Polyhexamethylene Guanidinium and Sulphonated Nitrosonaphthols

Figure 6

Effect of pH on adsorption of 0.2 μg mL⁻¹ Cu(II), Fe(III), Co(II), Ni(II), Al(III), Zn(II), Pb(II), Mn(II), and Cr(III) on SiO₂–PHMG–NRS (a) and on SiO₂–PHMG–NNS (b). Mass of adsorbent-0.1 g, sample volume 10 mL, and shaking time 10 min.

(a)

(b)