Soluble liquids are water soluble formulations of active ingredients in water or in polar solvents. The active ingredient must be absolutely chemically stable in water and in the selected solvents.
In many cases actives are solutions of alkaline salts, thus sequestering agents are necessary to avoid flocculation of salts in field-rate dilution water. Often the biological activity of SL is linked to the presence of a biological activator or wetter to improve the penetration of the active ingredient into the cuticular layer.
|The general composition usually contains:|
|Active ingredient(s)||100 to 600 g/l|
|Surfactants||50 to 200 g/l|
|Buffers, sequestering||0 to 30 g/l|
|Water (and polar solvents)||up to 1000 ml|
The formulation must be chemically and physically stable and clear at the usual storage temperatures. For application in the field, soluble liquids must be obviously soluble in water of various hardness and temperature.
Soluble liquids have a strong hydrophilic character and have difficulties in wetting and penetrating the lypophilic barrier of the foliage. Surfactants used can be divided into two groups - wetting agents and biological activators, even if it is often difficult to differentiate the two properties. Most surfactants show both activities in a single compound.
Adjuvants are products able to improve the biological activity of an active ingredient or to provide a constant activity in various climatic or application conditions. They can affect droplet deposit, rain-fastness, translocation through cuticular layer etc. and in this way modify the activity of plant protection active ingredients.
As a result of regulations and environmental concerns, producers of plant protection compounds are looking for surfactants with low toxicity and low impact on the environment. Emulsifiable concentrates (EC) are liquid formulations products to be diluted in water forming oil-in-water emulsions which allow good emulsion stability, fineness, homogeneous distribution and penetration of active ingredients into crops.