Study On Imidacloprid Controlled Release Nano-Carrier And Sustained Pesticide Formulation

Though the use of pesticide holds the balance in agriculture, pesticide administrated conventionally is easy to be washed out and decomposed in natural conditions and therefore causes a big waste of both the pesticide and labor, as well as the pollution to the environment. To solve this conflict, we tried to load imidacloprid into PHSN by Specially designed Impregnating Drug Loading (IDL) method or Supercritical Fluids Drug Loading (SFDL) method, and then it was developed into a novel formulation of imidacloprid for its controlled release. This study proposed a method to evaluate the DI/DO value by combining a thermal gravity (TG) analysis and a dissolution test method in order to determine drug loading distribution on PHSN (drug inside or outside of the PHSN). The effects of molecular size of the loaded drug and different loading methods on DI/DO value were also investigated, and it was found that the drug with smaller molecular size could be encapsulated much easier into the inner part of the nano-carrier and higher DI/DO value would be achieved. Higher DI/DO value and better sustained release would also be accomplished by a supercritical fluids drug loading (SFDL) method due to its high pressure, as compared with the impregnating drug loading (IDL) method. However, the operating cost of SFDL was much higher than IDL as well.Employing novel formulation of imidacloprid for controlled release, we also prepared imidacloprid wettable powders (WP) for controlled release and imidacloprid effervescent tablet (ET) for controlled release and explored the proper conditions of process technology. The controlled release behavior was investigated by dissolution and ultraviolet degradation experiments. It was found that our imidacloprid WP and imidacloprid ET have good controlled release capabilities. Self-made imidacloprid WP (effective components:39.1%; wetting time:82s;90%of particles size:1～7μm; suspended rate:76.5%) can meet the basic requirement of WP and self-made imidacloprid ET (effective components:19.3%; disintegration time:3.5min; friability:0.29%;90%of particles size:6～11μm; suspended rate:78.5%) can also meet the basic requirement of ET.