Table 4 Experimental data of the suitable buffer solution for the formation of the PAP azo complexes (Ia and lb)
Ligand | Co(II) | Ni(II) | Cu(II) | Zn(II) | ||||
|---|---|---|---|---|---|---|---|---|
Buffer pH | color | Buffer pH | color | Buffer pH | color | Buffer pH | color | |
Ia | Universal 9 | Yellow–green | Universal 6 | Pink | Universal 13 | Red | Universal 10.5 | Bright-red |
Ib | Universal 9 | Dark red | Universal 9 | Orange-Red | Universal 10 | Red | Universal 9.5 | Orange–red |