In the present experimental study, we describe the high capacity of a poly(amido amine)-tris(hydroxymethyl)amidomethane dendrimer for the physical adsorption of various chemical species (ligands), namely, cationic copper, anionic nitrate, and polyaromatic hydrocarbon phenanthrene. A pH-dependent specificity was observed for the dendrimer in hosting the chemical species, and the stoichiometric ratios of their binding were determined using UV-vis spectrophotometry. Specifically, cationic copper and anionic nitrate coordinated with the amine groups of the dendrimer through complexation and electrostatic interaction, while phenanthrene partitioned into the dendrimer interior through hydrophobic interaction. The binding and dielectric properties of the dendrimer-ligand complexes were further examined by microfluidics, at pH values optimized for the dendrimer and for species of picomolar concentrations. This study points to the vast potential of using tris-dendrimers for supramolecular assembly, environmental remediation, and nanomedicine.