Many agrochemical formulations carry a labelled shelf life of around two years from manufacture, and some are longer. The real figure depends on the active, the formulation type, the packaging and how the product is stored.
Shelf life is not a rule of thumb. It should come from stability data on the actual product in the actual pack, and in many countries the approved figure is part of the registration.
How stability is tested
Formulators use standard CIPAC methods so results can be compared. Three tests do most of the work.
- Accelerated storage, commonly 14 days at 54 °C (CIPAC MT 46), is a quick screen that is often taken as a rough guide to about two years at moderate temperature.
- Low-temperature stability, typically 7 days at 0 °C for liquids, checks for crystals, separation or other changes in cold conditions.
- Real-time storage, at ambient temperature over the full claimed shelf life, is what many regulators expect to confirm the claim.
What is measured after storage
After storage, the lab measures active content again, along with the physical properties that matter for the type. These include suspensibility for an SC, emulsion stability for an EC and dispersibility for a WDG. A product can keep its active content and still fail because it has caked or separated.
Some actives also form new impurities as they break down. Where a breakdown product is toxicologically relevant, regulators may ask for it to be measured after storage as well.
What shortens shelf life
- The active breaks down, often faster with heat, light, moisture or the wrong pH.
- Suspension products settle and cake hard, which stops them pouring and dispersing.
- Crystals grow in solutions and emulsions after cold spells.
- Solvent escapes through packaging, which raises concentration and swells or panels bottles.
- Damaged seals or closures let in air and moisture.
The role of packaging
Packaging is a frequent cause. See agrochemical packaging for how coex and barrier packs reduce solvent loss. Stability data is only valid for the pack it was tested in, so a change of bottle can mean new tests.
How to protect shelf life as a buyer
Shelf life starts at manufacture, not at arrival. Months in production, transport and customs come off what your customers receive. Plan for it in four ways.
- Ask for accelerated and real-time stability reports for the exact formulation and pack.
- Specify in your contract the minimum remaining shelf life at loading, such as a set number of months from the date of manufacture.
- Check manufacturing dates on packs during pre-shipment inspection, so old stock is not shipped as new.
- Store in a cool, dry, shaded warehouse after arrival, and sell oldest stock first.
Retesting old stock
Some countries allow you to retest product near expiry and extend its date, while others forbid it. Check with your regulator before you relabel any stock. Where retesting is allowed, use the same tests as the original release, and keep the results with the batch records.
Next step
We check stability data and manufacturing dates before loading, and have lots tested against your specification. Book a free sourcing review to plan your order.