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Key R&D projects - Q3 - 2019

Interest is shifting towards salt-tolerant ion exchange media that enable either capturing out of a biological feedstock at physiological conditions or direct processing of target fractions without dilution.

Purification of monoclonal antibodies (mAbs) require affinity chromatography, which involves binding antibodies to the agarose beads before eluting using a salt solution. The next stage is polishing using an IEX resin. To save money and time diluting the sample, a salt-tolerant IEX can be used instead.

As such, w
e are adapting our Praesto® agarose jetting technology to expand our ion exchange range beyond the current Jetted SP and Q 35 μm portfolio.

Soon we will finalise the design of a new range - Praesto XS - a salt tolerant strong cation exchange resin with very high capacities (100 mg IgG/mL), even under higher salt concentrations.

Purolite will provide full application support services to optimize conditions and ease of use.

How is it made?

This is achieved by homogeneous polymer chains of sulfonic acid functional monomers that are grafted from the surface of the pores and exterior of the jetted uniform agarose beads. 

This provides a robust, salt-tolerant surface.

What sizes are available?

Two bead sizes will be available:
  • Praesto XS50 -  a 50 µm bead for excellent separation. 
  • Praesto XS35 - a 35 µm bead offering powerful high resolution for the most challenging of separations.

What's the difference?

Uniform agarose beads are available only from Purolite.

These beads are unique and provide faster mass transfer, more concentrated elution profiles and lower buffer consumption compared to other beads in this class, such as CaptoTM S ImpAct or PorosTM XS. 

Unlike styrene-based resins, the innovation behind Praesto XS allows for alternative storage solutions, such as 2% Benzyl Alcohol. 

This addresses the trend to reduce the use of flammable storage solutions, which have historically been more commonly used.

Chromatograms - Resolution

5/50 Column

Chymotripsinogen 4mg/ml, Cytochome C 6mg/ml, Lysozyme 5mg/ml, MES buffer pH 6.2


Praesto XS 35 and 50 µm jetted uniform agarose beads are a range of strong cation exchanger agarose resins designed for polishing of monoclonal antibodies (mAbs) and a wide range of other biomolecules.

  • Provides effective removal of impurities (prA, HCP, charged variants, aggregates) from the monomer target product, even with today's challenging high titre Mab feedstocks. 
  • High capacity remains even in the presence of higher salt concentrations reducing non value added UF/DF steps and helps streamline process flow
  • Praesto Jetted XS resins provide high recovery and efficient impurities removal through powerful resolution as a result of the uniform beads matched with ionic capacities.