Apart from the active substances, plant protection products also contain co-formulants which give the product the necessary properties for application. They make plant protection products easy to handle, apply and store. They can improve operator safety when spraying and help disperse the active substances evenly in the spray liquid and help spread these on the plants. Co-formulants can consist of several components.

The preparation of a plant protection product made up of active substances and co-formulants is called a formulation. It is the task of formulation chemistry to find the optimum preparation for the plant protection product. There are various formulation types, e. g. water dispersible granules or emulsifiable concentrates. A list of formulation types can be found in the FAO/WHO Manual on Pesticide Specifications. The chemical, physical and technical properties of plant protection products may not significantly deteriorate over a period of at least two years. In order to test this, general and specific FAO/WHO specifications include the corresponding criteria and test methods. As a rule, formulations are improved constantly even after authorisation.

As part of the authorisation procedure, chemical, physical and technical properties are assessed according to the specifications of Regulations (EU) 284/2013. Apart from the EU provisions there are general and specific FAO specifications.

In order to acquire the corresponding data, appropriate test methods must be available. These are developed for formulations among others by the German-speaking working group for plant protection product formulations (DAPF) and – as far as necessary – validated in collaborative trials. Here, they are examined to see whether the methods in the various laboratories lead to comparable results. The DAPF also prepares publications by international organisations, particularly for the Collaborative International Pesticides Analytical Council (CIPAC).