Capto™ hydrophobic interaction chromatography (HIC) resins are designed for high-throughput capture, intermediate purification and polishing steps of a wide range of biomolecules in bioprocess applications. These resins are based on high-flow agarose and offer excellent resolution in bioprocessing.

You can pack Capto™ HIC in AxiChrom™ columns to allow high flow velocities and high bed heights and increase the productivity and flexibility in your process design. To achieve effective purification, you need to be sure that the resin is efficiently packed. Poorly packed columns can lead to costly disruptions and loss of your valuable product. Robust and verified packing and testing methods can eliminate such concerns and risks.

This article explains best practices to help you efficiently pack Capto™ Phenyl (High Sub), Capto™ Butyl, Capto™ Octyl, Capto™ Phenyl ImpRes, and Capto™ Butyl ImpRes chromatography resins in our AxiChrom™ chromatography columns.

Example results are shown in the accordions at the bottom of this page.

Capto™ chromatography resin characteristics

Capto™ chromatography resins are based on highly rigid agarose that allow high flow velocities, which is essential for raising productivity in large-scale operations. These resins offer you a wide range of bed heights and flow velocities. Capto™ resins are divided into two groups depending on average bead size.

Capto™ Phenyl (High Sub), Capto™ Butyl, and Capto™ Octyl have an average bead size of 75 μm and are used for capture and intermediate purification steps. The pressure-flow specification in large columns is 600 cm/h at less than 0.3 MPa (3 bar, 43.5 psi) and at a 20 cm bed height (tested with water at 20°C in a 1 m diameter column).

Capto™ Phenyl ImpRes and Capto™ Butyl ImpRes resins have an average bead size of 40 μm giving you high resolution in your bioprocessing. The pressure-flow specification for Capto™ ImpRes in large columns is 220 cm/h at less than 0.3 MPa (3 bar, 43.5 psi) at a 20 cm bed height (tested with water at 20°C in a 1 m diameter column).

General packing considerations


The height of a gravity-settled bed differs from the height of a bed settled under low flow (consolidated) due to the properties and the behaviour of the resin under different conditions. Therefore, you should separate the compression factor (CF) from the packing factor (PF). For example, in water in AxiChrom™ 50, when consolidated at 60 cm/h, the PF is 1.18 and the CF is 1.10 for Capto™ Butyl ImpRes.

Equations to calculate CF, PF, and column volume (CV) are shown below:

Compression factor, CF = Lsettled / Lpacked
Packing factor, PF = Lcons / Lpacked

Lsettled = bed height measured after settling by gravity
Lcons = consolidated bed height, that is, bed height measured after settling the resin at a given flow velocity
Lpacked = packed bed height  
CV = Lpacked × AC

AC = cross-sectional area of the column

When packing AxiChrom™ columns, PF is used in the packing procedure to calculate the final packed bed height after the consolidation step. CF is used in the chromatography resin preparation step to calculate the resin volume needed to pack a desired bed height.

Properties of Capto™ HIC resins in various packing solutions

Capto™ HIC resins settle quickly in water, in 20% ethanol, and in salt solutions for packing. When you use these solutions, remember to rinse tubing and nozzles directly after packing to prevent clogging of the flow path.

Adding salt to packing solutions slows the settling of the resin beads and allows them to settle less tightly. Therefore, it is very difficult to measure slurry concentration by gravity with salt-based solutions. However, the slurry concentration method described below allows for quick and accurate determination of slurry concentration.

For example, when Capto™ HIC ImpRes resins are settled at 60 cm/h, the consolidated bed height will be up to 7% higher in salt solution and sodium hydroxide (NaOH) solution and up to 4% in 20% ethanol compared to in water. The effect can be compensated for by using different PF. However, for optimal performance of the packed bed, we recommend specific packing solutions for different column types and sizes, which is further described in this article.

Slurry preparation

Capto™ HIC resins are supplied in 20% ethanol. Before packing, transfer the resin to the packing solution as described in the instructions for the column that you intend to pack.

Preparing the resin to form a slurry can be performed manually by shaking/stirring or using a mixer such as Media Wand™ slurry mixing and transfer tool. Shaking gives good results but is often not practical for larger volumes. When stirring, it is preferable to use soft stirrers without sharp edges. Media Wand™ suspends the resin directly in the container and transfers the slurry to BioProcess™ Resin Mixer in one operation, which makes it suitable for large-scale packing.

To achieve the correct amount of chromatography resin for packing to target bed height or compression, it is important that you measure slurry concentration correctly. When you prepare the slurry, start by calculating the chromatography resin volume (V) needed to pack the desired bed height. You can determine the slurry concentration in several ways, but to get an accurate slurry concentration of Capto™ resins, we recommend the Slurry Concentration Kit, which contains all the materials required for determination of slurry concentration.


To utilize the full flow potential of the Capto™ HIC resin, we recommend using AxiChrom™ in your process. The flexibility of column diameters and bed heights gives you full utilization of Capto™ HIC resin flow capacity, allowing for processes with increased bed heights if your floor space is limited or at lower bed heights and larger diameters to decrease process time. We have described packing Capto™ HIC resins in AxiChrom™ columns using the custom mode feature of Intelligent Packing. We have also described each packing method in relation to a specific packing solution. Deviation from use of the packing solutions described may have significant impact on the PF and subsequently on the packing result. The packing result and bed performance are well withing normal acceptance criteria for a well packed bed and ensure robust and stable process performance.

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