Intermediate Purification

Intermediate Purification Process Step

The partially purified feedstock from the capture step will have a higher target concentration and relatively less complex impurity profile (also at higher concentrations). The intermediate purification step uses chromatography's resolving power to separate the target away from other impurities of the feedstock. Because of this, and the improved fluid flow properties, resin particle sizes of 65 µm and smaller are used. In many cases, more than one intermediate purification column may be necessary to achieve the desired degree of product purity.

The role of resin efficiency (particle size) and selectivity (ligand and pore size) become more important for intermediate purification. The question for the process chromatographer is "What percent of dynamic binding capacity can I load the resin to and still have adequate resolution from most impurities?"

Intermediate purification steps typically use smaller particles than capture steps. The viscosity of the intermediate feedstock and the operational pressure limits of the chromatographic hardware used, determine the most appropriate particle size for this process step.

Many commercial TOYOPEARL and TSKgel PW bulk resin products are offered in particle sizes from 100 µm to 20 µm and have the same methacrylic polymer backbone. The selectivity of feedstock components on these resins remains the same regardless of bead size.

Tosoh Bioscience has commercial products with the following particle sizes for a typical intermediate purification step:

Grade Particle size range
Medium (M)  40-90 μm 
Fine (F) 30-60 μm 
Superfine (S) 20-50 μm
(30) 20-40 μm 


Approximate dynamic binding capacities for typical intermediate purification resins:

Mode   Typical Protein Antibody 
Ion Exchange » up to 200 mg/mL up to 150 mg/mL
Hydrophobic Interaction » up to 60 mg/mL up to 45 mg/mL
Hydroxyapatite » n.a. > 30 g/L

Please click on the mode of interest for additional product information.


Chromatography Particle Size TOYOPEARL Resin
Anion Exchange » 65 µm SuperQ-650M
Anion Exchange » 45 µm NH2-750F
Anion Exchange » 35 µm SuperQ-650S
GigaCap Q-650S
Cation Exchange » 65 µm SP-650M
Cation Exchange »  45 µm Sulfate-650F
Cation Exchange » 35 µm SP-650S
GigaCap S-650S 
Hydrophobic Interaction » 65 µm  Butyl-600M

Hydrophobic Interaction » 35 µm Butyl-650S
Hydroxyapatite » 39 µm Ca++Pure-HA