Suspension concentrate (SC)
Suspension concentrate (SC) formulations consist of having a solid active ingredient dispersed in water.
SCs have grown in popularity due to benefits such as absence of dust, ease of use and effectiveness when compared to other formulation types such as emulsifiable concentrate (EC) and wettable powder (WP). To formulate a stable SC, the active ingredient must remain insoluble under all temperature conditions.
- Water based hence it provides good safety and user convenience
- Suitable for many active ingredients with low water solubility
- Absence of dust
- Absence of flammable liquids
- Small particle size of the active ingredient
- Adjuvants can be built-in for bio enhancement
- Not compatible with water soluble active ingredients
- Crystal growth can be a problem if the active is partially soluble in water
- Long term stability issues
- Stability upon dilution
The Formulator's Toolbox (Full Version)
Products recommended for SC
The use of polymeric dispersants is highly recommended due to their higher molecular weight, large repulsive barrier and many anchoring groups per molecule. This enables highly loaded, stable suspension concentrates to be formulated. We have a range of dispersants each with a specific area of high performance.
It is important to include a wetting agent as during the milling process, fresh surfaces are generated which are generally of non-polar nature and will flocculate together rapidly. This could lead to increased viscosity and even mill blockage. Including a wetting agent overcomes this as it replaces air and prevents agglomeration, allowing dispersants to perform. Wetting agents can also provide some dispersion.
If an SC is not properly structured, the formulation can breakdown resulting in solid particles settling to the bottom of the formulation. This leads to reduced shelf life stability and poor performance in the field. The inclusion of a rheology modifier helps overcome this issue by increasing the viscosity of the formulation, providing improved stability.
In comparison to OD formulations, where the continuous oil phase acts as an adjuvant, SC formulations can be considered less efficacious due to the continuous phase being water. To enhance the bioavailability of the active ingredient, adjuvants can be incorporated in SC formulations.