Immobilized Metal Affinity Chromatography
| Metal Ion | Nickel or Cobalt |
| Ligand | IDA (iminodiacetic acid) and NTA (nitrilotriacetic acid) |
| Capacity | Ni-NTA > Co-NTA > Ni-IDA |
| Affinity | Ni2+ > Co2+ |
| Specificity | Co2+ > Ni2+ |
| Imidazole Elution | 250 mM (Ni) > 150 mM (Co) |
| EDTA/DTT Resistance | NTA > IDA |
| Re-chargeable | NTA > IDA |