Effect of Concentration of Chemically Attached Mercaptopropyl Groups on the Silica Surface on the Sorption–Photometric Determination of Palladium(II) and Silver(I) as Their Complexes with Attached Groups and Dithizone

The effect of the concentration of mercaptopropyl groups chemically attached to a silica surface in the range from 0.18 to 0.76 mmol/g on the formation and color intensity of Pd(II) complexes with the attached groups, as well as mixed-ligand complexes of palladium(II) and silver(I) with attached mercaptopropyl groups and dithizone is studied. It is shown that, with an increase in the concentration of the attached mercaptopropyl groups, the color intensity of sorbents containing an equal amount of the adsorbed palladium(II) increases. In the case of the formation of mixed-ligand complexes of palladium(II) and silver(I) with the attached groups and dithizone, with an increase in the surface concentration of the attached groups, the intensity of the sorbent color decreases. Procedures for the sorption–photometric determination of palladium(II) as complexes with the attached groups and palladium(II) and silver(I) as surface mixed-ligand complexes are developed. It is concluded that, to achieve low limits of detection of elements as their complexes with the attached groups by the sorption–photometric method, the concentration of the attached groups should be maximum, and to achieve low limits of detection of elements as their mixed-ligand complexes with the attached groups and dithizone, the concentration of the attached groups should be minimum.