ABSTRACT
The procedure consists of dispersing the active agent in an aqueous starch xanthate solution and, subsequently, crosslinking the starch xanthate either oxidatively, with multivalent metal ions, or with difunctional reagents such as epichlorohydrin. Cereal flours, which contain about 10% protein along with starch, also can be xanthated and used as an encapsulating matrix. The xanthates are much less viscous, and a solids content of 50% or higher can be easily achieved. Other polyols can also be used for encapsulation via xanthation. Polymers, such as cellulose and polyvinyl alcohol, are easily xanthated, although one might not apply the same recipe as with starch. Shelf life of the starch-encapsulated pesticides is good, and there is no appreciable loss on storage during at least 1 year. Chemical and biological evaluation indicate that differences in controlled release can be achieved by selection of the starch xanthate and oxidant used in the formulation process.
