Com o objetivo de estudar o comportamento do herbicida (R,S)-haloxifope em solo tropical realizouse este trabalho para determinar sua dissipação num latossolo roxo eutrófico. Para isso, amostras de solo (em triplicata) foram previamente tratadas com haloxifope metil racêmico e incubadas a 25oC por 0, 6, 10 15, 30 e 60 dias. Após cada período de incubação as amostras foram submetidas a extração em ultra-som, purificadas com diclorometano, evaporadas em rotavapor e ressuspendidas em metanol. O

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... rato metanólico foi analisado por Cromatografia a Líquido de Alta Eficiência (CLAE). Os dados cinéticos mostraram meia-vida inicial (t0½) de 7,38 dias, o que pode estar relacionado com a atividade microbiana de caráter enantiosseletivo no solo. (R,S)-HALOXYFOP DISSIPATION IN A TROPICAL LATOSOIL Abstract The aim of the work was to study the behavior of the herbicide (R,S)-haloxyfop in a tropical soil. This work was realized to determine its dissipitaion in an eutrophic purple latosoil. Three replicates of soil samples were previously treated with methyl racemic haloxyfop and incubated at 25ºC for 0, 6, 10, 15, 30 and 60 days. After each incubation period the samples were submited to ultra sound extraction, purified with dichoromethane, evaporated and ressuspended in methanol. The methanolic extract was analysed by High Performance Liquid Chromatography (HPLC). The kinetics data revealed initial half life (t01/2) of 7.38 days, which can probably be related to the microbial activity with enantioselective character in soil.