THE PHYSICOCHEMICAL AND BIOLOGICAL CHARACTERIZATION OF INSECTICIDE DELIVERY SYSTEMS PREPARED BY ENTRAPMENT IN LATEX DISPERSIONS (POLYMETHYL METHACRYLATE, METHYL PARATHION)
Abstract
The purpose of this research was to assess any potential advantages of using molecular scale entrapment in polymeric latices as a method of improving the performance of insecticidal agents. Methyl parathion was selected as model insecticide due to its instability and toxicity. Two molecular dispersion techniques were employed. One involved the entrapment of methyl parathion in a latex of poly (methyl methacrylate-methacrylic acid) copolymer at a 70:30 ratio of the ester to the acid. Solid entrapment products were obtained by coagulation of the latex with an alcohol solution of the insecticide material followed by drying and milling of the coagula. The second entrapment method involved the preparation of an ethylcellulose pseudolatex in which methyl parathion was entrapped during the preparation of the colloidal dispersion. This technique involved preparing a microemulsion of an organic solvent solution of methyl parathion and ethylcellulose in water followed by vacuum stripping of the solvent, leaving behind a colloidal dispersion of ethylcellulose beads containing dispersed methyl parathion in water. Solid entrapment products were also prepared using this technique, by continuing the vacuum distillation to complete product dryness. These experimental insecticide formulations were compared for physical and chemical stability, insecticidal activity in two insect species and toxicity in a warm blooded animal with a conventional mixture of methyl parathion with calcium carbonate, and a commercial microencapsulated product. X-ray diffraction studies were performed on the solid polymer entrapment products, on physical mixtures of the acrylate and cellulosic polymers with methyl parathion and on the conventional calcium carbonate mixture. The diffraction pattern of the insecticide disappeared in the entrapment products, not in the physical mixtures of the polymer and insecticide. The presence of methyl parathion in the entrapment systems was verified by infrared spectroscopy. This indicated that the insecticide was molecularly dispersed in the two entrapment systems (employing the latex and pseudolatex). The X-ray pattern of methyl parathion was very weak in the calcium carbonate mixture, which was attributed to the strong absorption of the X-rays by calcium carbonate. . . . (Author's abstract exceeds stipulated maximum length. Discontinued here with permission of school.) UMI
Degree
Ph.D.
Subject Area
Pharmacology
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