title: Solvent and surfactant enhanced solubilization, stabilization, and degradation of amitraz.
abstract: In an effort to help with the development of effective dip vat management and waste disposal strategies this study determined how solution properties such as pH, buffer composition, ionic strength, temperature, solubility in organic solvents and the addition of commonly used solubilizing agents influenced the hydrolysis of amitraz. Amitraz degrade by means of hydrolysis described by a pseudo-first order rate process and a type ABCD pH rate profile. Hydrolysis increased with temperature and was fastest at low pH, slowest at neutral to slightly alkaline pH, and slightly increased above pH 10. However, buffer concentration and ionic strength influenced the hydrolysis rate and had to be accounted for before constructing a pH rate profile. Hydrolysis seems to depend on the dielectric constant of solvent mixtures and was fastest in water, slower in propylene glycol and ethanol solutions, and slowest in DMSO mixtures. In surfactant solutions, anionic micelles enhanced and cationic micelles retarded the hydrolysis rate. The magnitude of micellar effects decreased with increasing concentrations of the surfactants. The increased solubility and faster hydrolysis of amitraz in the sodium lauryl sulfate solutions showed that anionic surfactants potentially could be used for cleaning up amitraz spills, because it both solubilized the drug and catalyzed hydrolysis.
authors.affiliation: Research Institute for Industrial Pharmacy, School of Pharmacy, Potchefstroom University for CHE, Potchefstroom, South Africa.
authors.forename: Charmaine M
authors.initials: CM
authors.lastname: van Eeden
authors.forename: Wilna
authors.initials: W
authors.lastname: Liebenberg
authors.forename: Jan L
authors.initials: JL
authors.lastname: du Preez
authors.forename: Melgardt M
authors.initials: MM
authors.lastname: de Villiers
mesh_terms: D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007306:Insecticides / Q000737:chemistry*; D007700:Kinetics; D008823:Micelles; D009994:Osmolar Concentration; D012989:Soil Pollutants / Q000032:analysis*; D012995:Solubility; D013501:Surface-Active Agents / Q000737:chemistry*; D013696:Temperature; D014052:Toluidines / Q000737:chemistry*
chemical_list: D007306:Insecticides; D008823:Micelles; D012989:Soil Pollutants; D013501:Surface-Active Agents; D014052:Toluidines; C014983:amitraz