The apparent solubility in water of 2-ethylamino-4-isopropylamino-6-methylmercapto-s-triazine [ametryne], 3-(3,4-dichlorophenyl)-1,1-dimethyl urea [diuron], and 2-chloro-4-ethylamino-6-isopropylamino-s-triazine [atrazine] was increased when a surfactant was added to the water. At 0.5% surfactant concentrations, considerable variation in solubility was found, both as regards the herbicide and surfactant used, as measured by ultraviolet absorption spectrophotometry. The two triazines were more soluble in cationic surfactants, followed by anionic and nonionic; diuron was more soluble in cationic followed by nonionic and anionic types.
Minimum lethal levels of surfactant in water for 2 week old cucumber plants varied from about 0.1% for the cationic to 0.2% for most nonionic and 1.0% or more for anionics of the alkyl aryl sulfonate type.