950 (2002) 157–166 Journal of Chromatography A, www.elsevier.com / locate / chroma Determination of herbicides and metabolites by solid-phase extraction and liquid chromatography Evaluation of pollution due to herbicides in surface and q groundwaters a, a a * ´ ´ ´ ´ Rita Carabias-Martınez , Encarnacion Rodrıguez-Gonzalo , Eliseo Herrero-Hernandez , b a ,1 ´ ´ Francisco Javier Sanchez-San Roman , M. Guadalupe Prado Flores a ´ ´ ´ ´ ´ Departamento de Quımica Analıtica, Nutricion y Bromatologıa, Facultad de Quımica, Universidad de Salamanca, Plaza de la Merced s / n, 37008 Salamanca, Spain b ´ ´ Departamento de Geologıa, Facultad de Geologıa, Universidad de Salamanca, 37008 Salamanca, Spain Received 12 June 2001; received in revised form 14 December 2001; accepted 14 December 2001 Abstract A procedure based on solid-phase extraction (SPE) has been developed for the simultaneous preconcentration of three widely used herbicides and seven of their most common degradation products. The compounds studied were atrazine and its metabolites, desethylatrazine, desethyldesisopropylatrazine (DEDIA), 2-hydroxyatrazine, desethyl-2-hydroxyatrazine and desisopropyl-2-hydroxyatrazine (DIHA), terbutryne and its metabolite 2-hydroxyterbutylazine, and chlorotoluron and its metabolite 3-chloro-4-methylphenylurea. A HPLC system with diode array detection was used for the separation, identification and quantification of all these analytes. In the SPE preconcentration step, different types of sorbent were studied: C on silica and polymeric sorbents (Oasis and LiChrolut EN), the best results being obtained with the 18 styrene–divinylbenzene cartridge and when the elution was performed with methanol and ethyl acetate. The detection limits 21 21 obtained were between 0.1 mgl for DIHA and DEDIA and 0.02 mgl for the other analytes. The method used permitted the determination of these herbicides in drinking water at the concentration levels demanded by current legislation. The proposed method was used to evaluate the presence and evolution with time of these herbicides and their degradation products in samples of surface and ground waters from agricultural zones of the provinces of Salamanca and Zamora (basins ˜ of the Rivers Guarena and Almar), Spain.  2002 Elsevier Science B.V. All rights reserved. Keywords: Water analysis; Environmental analysis; Pesticides q Presented at the 30th Scientific Meeting of the Spanish Group of Chromatography and Related Techniques / 1st meeting of the Spanish Society of Chromatography and Related Techniques, Valencia, 18–20 April 2001. ´ E-mail address: rcm@gugu.usal.es (R. Carabias-Martınez). *Corresponding author. Tel.: 134-923-294-483; fax: 134-923-294-574. 1 ´ ´ ´ ´ Permanent address: Departamento de Produccion Agrıcola y Animal, Division de Ciencias Biologicas y de la Salud, Universidad ´ ´ Autonoma Metropolitana-Xochimilco, 04960 Ciudad de Mexico, Mexico. 0021-9673 / 02 / $ – see front matter  2002 Elsevier Science B.V. All rights reserved. PII: S0021-9673(01)01613-2