Please find some commonly asked questions regarding our Praesto® Ion Exchange resin range.

We've tried to be comprehensive, but if you have a question for one of our dedicated specialists, please contact us for fast, reliable support.


I am using several GE Healthcare ion exchange resins, which Purolite resins do you recommend as alternatives?

We have several ion exchange resins designed to be drop in replacements without any changes to buffer formulations for GE Healthcare resins, including the Capto, Capto ImpRes and Sepharose family of products. Contact us to discuss specific process details so we offer our expert advice.

I am looking for improved separation with my ion exchangers to improve aggregate clearance, can Purolite help?

We recommend testing Praesto Jetted SP35 and Praesto Jetted Q35.  These two polishing ion exchangers use a uniform 35 micron bead, and traditional SP and Q chemistry. The uniform bead offers very powerful separation.

Purolite has developed uniform agarose bead technology, which offers greatly improved mass transfer rates, resulting in a more concentrated elution pool, translating to less buffer usage. A key benefit for process scale-up. 


How do you clean DNA from Anion Exchange resins?

It is well known that it is very difficult to remove DNA from Anion Exchange resins. The process typically takes repeated treatment with a high salt concentration and NaOH.

What would you advise for endotoxin clearance?

For endotoxin clearance any of our Praesto® Q AIEX would be suitable. These are available in 45 μm , 65 μm & 90 μm bead sizes.

Praesto® Q90 would be the least expensive and would be suitable, but our recommended particle size would be 65 µm.  This gives optimal performance and pressure flow gains.


Which conductivity should be used during load of Ion Exchange resins?

Praesto® Q is a "traditional" resin so, in principle, the lower the conductivity, the higher the capacity.

However, it will also depend on the charge of your particular protein. As a rule of thumb, try to stay below 3
mSc during loading.

Do you have any information about the compatibility of your resin with solvents such as acetone, DMF, and THF?

Praesto® Pure and IEX resins are compatible with these organic solvents. They tend to swell to a different extent with each solvent, but when the solvents are displaced they return to their original size. 

Agarose is quite resilient to most conditions apart from pH levels lower than 2 and strong redox agents. 


What are the CIP recommendations for Praesto® SP45?

For Praesto® SP45 we would recommend a high conductivity strip at a neutral or higher pH (1.0 M NaCl or 0.5 NaAc - if you want to avoid chloride ions) before CIP with 0.5-1.0 M NaOH.

If there is very little fouling it would be suitable to run 1.0 M NaOH directly after elution as a combined strip and CIP.,

I use Q Sepharose® - which Praesto® resin would you recommend?

Test the Praesto® Q65 under the same conditions used in the current process with Q Sepharose® 6 FF. There are differences in particle size, rigidity, and porosity while the ligand density is in the same range.

With Praesto® Q65 you should expect significantly higher dynamic binding capacities, lower buffer consumption and more concentrated product pools.

What conditions do you recommend for the CIEX step?

We recommend using acetate (25-50 mM NaAc, pH 5.0-5.5) for the cation exchange step. Typically, load at pH 5.0 and elute with an acetate gradient.

It can be difficult to elute from the cation exchanger at sufficiently low conductivity. One way is to elute with a pH gradient at low conductivity.

Alternatively, increase the pH at low conductivity while the mAb is still bound to the resin in order to decrease the conductivity in the product pool. If necessary, the sample could be conditioned before the Q step with dilution (potentially in-line dilution) in order to bring down the conductivity. 

Another alternative is to run the Q step before the CIEX step.

When packing Praesto® Jetted SP35, what would happen if packed into a column which has 20 micron frit? Would the resin be loose or jammed?

As a rule of thumb the frit or net should be at least a third or less than the mean particle diameter of the resin.

What should be used for the removal of antibody fragment dimers from monomers?

Most commonly CIEX, HIC, or multimodals are used, in that order. CIEX can also be used as an alternative to Protein A for capture. In that case the feed would need to have a conductivity below 5-7 mSc to achieve suitable capacity.

Our small-scale data shows higher pressure than at large scale, why?

Large-scale experiments are more relevant, as they measure the pressure drop over the resin. In smaller scale experiments, pressure restrictions from tubing and valves contributes to additional pressure drop.

Do you undertake any custom projects?

Our team of world-class researchers, polymer chemists and application scientists are experts at developing novel, customized products that meet the diverse requirements and expectations of our customers. 

Whether you need a customized particle size, functional group, porosity or ligand density, Purolite Life Sciences can help you.

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What is the recommended maximum running pressure of the 90, 65 & 45 micron beads?

We have not seen a significant difference in rigidity between the different particle sizes (45µm / 65µm / 90µm).

In smaller columns (5 cm diameter and smaller) we typically recommend to pack at 4 bar and not exceed 3 bar during operation. Data from larger columns suggests an optimal compression factor of 1.1 – 1.2.

Which IEX resins should be used to screen for an antibody with a pH of 8.4 – 9.1?

For cation exchange in bind-elute mode we would always recommend testing Praesto® SP45. For anion exchange in flow-through mode, Praesto® Q65 is the ideal choice.

How can acedic species be removed?

With regards to the reduction of acedic species, unfortunately there is no general protocol.

We recommend a simple shallow salt gradient at a pH where the product is stable. If there is no separation at all even at a moderate load, try a different pH.  If there is still no success, a pH gradient for elution should be used instead.


What are the bioburden levels on Praesto?

The current specification is <100 but we are working to lower to <20.

What is the average lead time for delivery?

For volumes up to 100 litres - average lead time is 4 weeks.

What is the storage life?

Currently, 4 years. We are conducting ongoing life time studies to continually update this figure

What are the endotoxins levels on Praesto®?

We benchmark our endotoxins levels at those similar to other market-leading products.

Are resins manufactured in a cGMP environment?

Resins are not required to be cGMP accredited but in manufacturing we follow GMP guidelines appropriate to the product and the application. All relevant national and international regulations are adhered to.

The resin has to be manufactured to a set protocol where all raw materials used in its production are documented, the production is defined and documented i.e. operators, quantities and operations undergone are all recorded.

The product needs to be defined against a specification and released as such – i.e. purity, concentration and other key performance characteristic which is required by the process/product, and GMP appropriate to the product and its application. 

What certification of quality has Purolite received?

We are certified to ISO 9001:2015 standards.


What are the sizes of your standard containers?

The minimum is 25 ml and, currently, the largest container is 20 L (with 10 L resin volume).

This is to satisfy on-site manual handling requirements but we can provide containers up to 60 L if required.

Is Purolite Life Science QMS certified?

Yes, our systems certified against global standard ISO9001:2015. The ‘QMS’ offers us a framework for our business processes, focusing on consistently delivering a product and service that meets our customer requirements and enhancing their satisfaction. Scope of the management systems captures the design, manufacture and sale process ensuring stringent quality requirements are maintained. Purolite Ltd is also ISO14001 and ISO45001 certified.

Which containers do you use for shipping purposes?

For 1-10 L resin volumes.we use a jerrycan. 

For 10-500 ml samples the resins are bottled.

All shipping containers are manufactured from HDPE.

Who is our accredited, certification body?

Purolite Ltd is certified via BSi, who in turn are accredited globally.  

Does Purolite Life Science consider other Healthcare guidelines?

Our customers’ requirements and intended use of our product is key for understanding ‘other’ regulatory and quality requirements. Therefore, we take guidance from both Pharmaceutical and Healthcare industries like IPEC-PQG for Excipient manufactures and ICH guidelines established to harmonise a global approach to technical requirements in the pharmaceutical industry. These translate into statutory requirements under  EU and FDA CFR21 legislation critical to customers intended market. Understanding  these requirements allows us to offer a product and service fit for its intended use.

Are Praesto® Product manufactured under cGMP conditions?

Production is not cGMP certified. However we adopt Good Manufacturing Practices prescribed in IPEC-PQG guidelines, our products are not tested to pharmacopeia monographs but industry method of test.

Are products controlled through supporting literature?

Yes, all commercial products are supported through comprehensive technical documentation; including Specifications, Certificates of Analysis. These are documented in our RSF (Regulatory support File).

Do you send CoA's with shipments?

Yes, all of our products are shipped with COA’s, MSDS and other regulatory documentation ensuring export and import condition are achieved.

Can I request additional certificates; Origin statement?

Yes, nonstandard requests  are processed through customer special instructions, defined during the Sales Order process.

Is there documented change control system?

Yes, part of our QMS Purolite operates a documented and controlled Management of Change. Customer notifications are issued for any major changes.

What is the Shelf Life of Praesto® products?

Generally our products are allocated 5 year shelf life, unless otherwise stipulated.


What is recommended storage buffer for Praesto SP45?

Typically, SP45 would be stored in 0.1 M NaOH after initial use. 20% ethanol, 0.2 M NaAcetate (no need to adjust pH) is also fine but is a much less effective bactericide. The acetate is added to prevent pH from decreasing over time which would happen in a plain 20 % ethanol solution in combination with a CIEX resin,