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 3

Adsorption isotherms of NRS on SiO₂–PHMG before (1) and after one (2), two (3), three (4), four (5), and five (6) treatments of SiO₂–PHMG–NRS with 10 mL of hot (50°С) 6 М  НСl. Mass of adsorbent-0.1 g, other details of experiments as listed in Figure 1.