It is critical when launching any new product that the stability of that product is thoroughly checked before it reaches its end user. You need to confident that your product is going to look, smell and behave in the same way at the end of its shelf life as it does on the day that it is manufactured. Knowing how your product is going to behave on the shelf, and taking steps to reduce and prevent the product degrading are critical parts of the development process.
If we take agrochemical products as an example, common product stability problems can include –
Settled Solids
Over time reactions can take place in the bottle leading to non-soluble materials forming – these settle out leading to sediment (as is sometimes seen in fruit-cordial concentrates). When these non-soluble materials occur in fertilisers, they are no longer accessible to the plant and so reduce the effectiveness of the fertiliser. Additionally, if the fertiliser is usually sprayed onto crops, this can cause blockages of spray equipment, causing delays and unnecessary expense as equipment is cleaned or replaced.
Blowing Bottles
Reactions between components and sometimes bacteria in the bottle can lead to a build up of gas, which can cause the bottle to deform and blow. On the shelf, this is unsightly and a clear indicator that something has gone wrong. In storage, this can cause boxes to break and spill their contents, or even entire pallets of boxes to break down.
Discolouration and Odours
For a fertiliser product, the pH can drift over time causing reactions to take place within the bottle. An alkaline pH can cause instability of ammonium based materials, causing an ammoniacal odour. Or where a product has drifted to an acidic pH when containing sulphur based materials, it can precipitate sulphur, leading to an eggy smell.
So how do you test stability? For customers wanting to take a new product to market it isn’t practical to have to make a sample and wait for up to two years before testing it. Therefore a technique that is often used is the ‘accelerated storage stability trial’. This involves heating a sample to a higher than ambient temperature and storing – usually for a few weeks or months – to simulate a longer storage time.
Other stability trials that should be undertaken on new products during the development process can include – a cold temperature trial, an ambient temperature trial and a tank mix trial.
Armed with the results from such trials you can quickly ascertain how a product is going to behave and then adjust the formulation accordingly. As the development process progresses, it is possible to determine where the instability lies and remove problem components or add other stabilisers in order to overcome any potential problems.
Fortunately many of the lessons learned for one product can often be applied to another, allowing the generation of knowledge and expertise in a given area. It isn’t just fertilisers that benefit from stability trials – suspensions and emulsions can separate and solid products can cake and discolour. The tests for each product type can vary but ultimately the desired outcome is the same – a product that will look and behave as expected for the end user.
At Grotech Production our experienced laboratory technicians are on hand to help and guide you through stability trials for your product – send us an email, or call 01405 761746 to talk to our team today.
