Determination of 2,4-dichlorophenoxyacetic acid and its major transformation product in soil samples by liquid chromatographic analysis O.P. de Amarante, Jr. a , N.M. Brito b , T.C.R. dos Santos a, *, G.S. Nunes a , M.L. Ribeiro b a Nucleus of Pesticide Residue Analysis (NARP), Department of Technological Chemistry, Federal University of Maranha ˜o, UFMA 65.080-040, Sa ˜o Luı ´s, Maranhao, Brazil b Chemistry Institute of Araraquara, State University of Sa ˜o Paulo, UNESP 14.800-900, Araraquara, Sa ˜o Paulo, Brazil Received 24 July 2002; received in revised form 14 January 2003; accepted 17 January 2003 Abstract The 2,4-dichlorophenoxyacetic acid (2,4-D) is one of the most applied herbicides around the world to control broad leave herbs in many crops. In this study, a method was developed for simultaneous extraction and determination of 2,4- D and its major transformation product, i.e., the 2,4-dichlorophenol (2,4-DCP), in soil samples. The herbicide and its degradation product were extracted twice from soil samples, after acidification, by dichloromethane on ultrasound system for 1 h. Both extracts were combined and filtrated in qualitative filter paper and Celite † . The total extract was concentrated in rotatory evaporator, dried under N 2 and finally dissolved in 1 ml of methanol. High Performance Liquid Chromatography with UV detection at 230 nm was used for analysis. Recoveries were obtained from soil samples fortified at 0.1, 1.0, 2.0, 3.0 and 4.0 mg kg 1 levels and the results varied from 85 to 111% (for 2,4-D) and from 95 to 98% (for 2,4-DCP). For both compounds, the limits of quantification were 0.1 mg kg 1 , which were the loss level at which the accuracy and the precision were studied. Nevertheless, the limits of detection, calculated by considering the blank standard deviation and the minimum concentration level, were 0.03 and 0.02 mg kg 1 , for 2,4-D and 2,4-DCP, respectively. This proposed method was applied to soil samples of eucalyptus crops, which was previously treated with the herbicide. Despite that, neither 2,4-D nor its degradation product were detected 30 days after the herbicide application. # 2003 Elsevier Science B.V. All rights reserved. Keywords: Degradation; Herbicide; Eucalyptus 1. Introduction The environment has been continually affected by the practices of agriculture, which include the extensive use of pesticides. Once in the soil, the pesticides behavior will be directly dependent of * Corresponding author. Fax:  /55-98-217-8245. E-mail address: teresant@terra.com.br (T.C.R. dos Santos). Talanta 60 (2003) 115  /121 www.elsevier.com/locate/talanta 0039-9140/03/$ - see front matter # 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S0039-9140(03)00113-9