Abstract

Present study pertains to preparation, characterization and evaluation of human guarded chlorpyrifos urea co-inclusion complexes for agricultural use. Chlorpyrifos a widely used organophosphate insecticide was co-included along with long linear chain rapidly complexing agent in urea lattice. A three component powder form comprising of urea as host cum fertilizer, oleic acid as an insect pheromone and an insecticide for killing/ disabling the insects was prepared. Resulting insecticide fertilizer amalgamation offered improvement in safe handling and formulation characteristics. Insecticide was engulfed in tunnels of hexagonal urea and is accordingly not accessible for either contact with skin or for inhalation/odor. Hence, personnel engaged in handling of chlorpyrifos will not be exposed to its toxic effects after co-inclusion in hexagonal urea. Insecticide will be activated/released only after chlorpyrifos urea co-inclusion complex comes in contact with water following switching on of automated water sprinkling system in agricultural fields. Steep reduction in mercaptan like odor of chlorpyrifos was observed following engulfment of chlorpyrifos in hexagonal urea lattice. Minimum proportion of long linear chain rapidly complexing agent required for co-inclusion of insecticide in urea lattice was determined calorimetrically. Chlorpyrifos urea co-inclusion complexes were characterized by Fourier transform infrared spectroscopy, X-ray powder diffraction, differential scanning calorimetry and ¹H-nuclear magnetic resonance spectroscopy studies. Regression analysis depicted gradual increase in heat of decomposition with corresponding increase in molar fraction of rapidly complexing agent. Increased heat of decomposition simply indicates better physical stability of complexes. These complexes chlorpyrifos urea co-inclusion complex revealed uniform formulation composition and improved dissolution profile of chlorpyrifos. Studies reveal insecticide fertilizer amalgamation to be a promising approach for formulation of poorly soluble hazardous insecticide into an effective rapidly soluble human guarded insecticide product with improved handling/formulation characteristics at minimal cost.