How are food and potable grade resins different from industrial grade resins?

All industrial grade ion exchange resins and adsorbents have low levels of organic leachables, which are released from the resin when new. With the resins used in foodstuff and potable water production, the resin manufacturers take additional steps to reduce these to much lower levels, so that they cannot affect the product being produced by the resin detrimentally. In addition, the composition of food contact and potable water resins need to meet relevant requirements or regulations. Industrial resins may not meet these requirements.

How does a manufacturer make a food or potable grade resin?

Some food and potable grade resins are totally unique and specially developed for specific applications and these resins, as part of their production process are specially treated at different stages of the production, or post-production, to provide a cleaner product. Where a product is available, both as industrial grade and potable grade resins, then the resin will have the same basic chemistry and work in the same manner, but again, it will have additional cleaning stages within the production process, or special post-treatment or cycling between different ionic forms that clean the resin, reducing leachables species from the resin when new.

Do food and potable water grade resins have a limited shelf life?

Yes, all manufacturers have a recommended shelf life for their products and it can be obtained from the manufacturer. These assume the resins have been stored correctly, in line with the manufacturers recommendations. These recommendations normally include being stored in their original packaging, undisturbed, indoors, away from direct sunlight and not subject to extreme temperatures of cold or heat, but may have other specific requirements.

See more information on national legislation here.

How are food and potable grade products identified?

Each resin manufacturer has either a unique brand name or they may add a prefix or suffix to the products name to identify it as a food or potable grade product. Each manufacturer can advise accordingly. The resins can sometimes be similar in performance and chemistry to their industrial-grade counterparts, but importantly the resins meet migration requirements. Food or potable grade products are often shown clearly on each resin manufacturers website.

If I purchase a food or potable water grade resin can I place it into the column and use immediately?

No, the resin may not be supplied in the required ionic form and requires regeneration to put it into the correct ionic form. Even if the resin is purchased in the correct ionic form, it is often still good practice to regenerate the resin if practical, if it is part of the plant’s normal operation. This regeneration is important, particularly if the product has been in storage, to ensure the product is placed in service in optimum condition. Each manufacturer has their own recommendations for each resin in each particular application. Where the resin is used in a non-regenerable application, the resin manufacturer will still have a recommended procedure to condition the bed before use.

How do I commission the column with new resin?

Discuss with your resin supplier, establish the resin manufacturers recommendation for that specific product in the application and follow them as a minimum requirement. Always test the initial product produced by the resin and fully satisfy yourself that the product being produced by the resin is of the desired quality and purity before placing the resin in service.

Is regenerant chemical purity important?

In food or potable water grade applications that employ resin regeneration, then the regeneration of resins must be with chemicals that do not introduce any contamination and are of high purity. Recommendations can be obtained from your resin manufacturer.

Do ion exchange resins require special care if resin sterilisation is undertaken?

Strong oxidising agents are detrimental to all ion exchange resins and so sterilisation of beds must only be undertaken with great care. Otherwise, irreversible damage can be caused. The chemicals used widely to sterilise pipework and tanks are often used at a concentration and contact time which would seriously damage the resin.

I am a non European ion exchange or adsorbent resin producer, can I join Soia group?

Only EU resin producers can join the Soia group.

I am an ion exchange or adsorbent resin user (OEM, end user,..) and have a regulatory question. Can I raise my question to the Soia group?

In general, regulatory questions should be answered by your resin producer/supplier. Some questions may be non-supplier specific, of pan EU interest. In this case, the Soia group can discuss these at their next meeting.

Ion exchange resins are polymers, are they therefore exempt from the REACH registration?

The manufacturer or importer of a copolymer will need to register the monomer(s), or any other substance chemically bound to the polymer at 2%w/w or greater, unless these substances have already been registered by the supplier or another actor up the supply chain. One exception is non-isolated intermediates, which are exempt from registration. (Ref.: Article 2 of REACH).

Are there regulatory requirements for cation resins used in dishwasher applications?

IER used in dishwasher applications in the EU do not require any drinking water nor food contact regulatory compliance.

Why does the substance information chart on the ECHA website show more hazard information compared to the information on the SDS of the ion exchange resin?

The substance information charts on the ECHA website reflect the information notified to ECHA through the SDSs issued by the economic operators (manufacturers, distributors, downstream users). As soon as 5% or more of the economic operators notify ECHA of a hazard, ECHA will list the hazard information on the substance information chart.

The substance information sheets on the ECHA website are CAS- and EC-number specific. For polymeric substances, like ion exchange resins, the CAS-number typically characterizes a polymer family and not a single substance. The chemical properties, like molecular weight, water solubility, etc., within the polymer family can differ substantially. These differences may lead to different hazard properties for products within the same polymer family.

Economic operators will issue SDSs listing the hazards specific for their products. As within a single specific polymer family with the same CAS-number, the final products can differ substantially, the SDSs for the different products can contain different hazard information.