TAPS is a chemical compound commonly used to make buffer solutions.
It can bind divalent cations, including Co(II) and Ni(II).
TAPS is effective to make buffer solutions in the pH range 7.7–9.1, since it has a pKa value of 8.44 (ionic strength I = 0, 25 °C).
The pH (and pKa at I ≠ 0) of the buffer solution changes with concentration and temperature, and this effect may be predicted e.g. using online calculators.
References
Machado, Carina M. M.; Gameiro, Paula; Soares, Helena M. V. M. (2008). "Complexation of M–(buffer)x–(OH)y systems involving divalent ions (cobalt or nickel) and zwitterionic biological buffers (AMPSO, DIPSO, TAPS and TAPSO) in aqueous solution". J. Solution Chem. 37 (5): 603–617. doi:10.1007/s10953-008-9265-3. S2CID 97906177. /w/index.php?title=J._Solution_Chem.&action=edit&redlink=1 ↩
Goldberg, Robert N.; Kishore, Nand; Lennen, Rebecca M. (2002). "Thermodynamic quantities for the ionization reactions of buffers" (PDF). J. Phys. Chem. Ref. Data. 31 (2): 231–370. doi:10.1063/1.1416902. http://structbio.vanderbilt.edu/wetlab/buffer.ioniz.pdf ↩
"Biological buffers". REACH Devices. http://www.reachdevices.com/Protein/BiologicalBuffers.html ↩