Journal of Chromatography A, 866 (2000) 137–146 www.elsevier.com / locate / chroma Determination of pesticides in waters by automatic on-line solid-phase extraction–capillary electrophoresis a b b b, * ´ ´ P. Hinsmann , L. Arce , A. Rıos , M. Valcarcel a Institute of Analytical Chemistry, Vienna University of Technology, A-1060 Vienna, Austria b ´ ´ Department of Analytical Chemistry, Faculty of Sciences, University of Cordoba, E-14004 Cordoba, Spain Received 22 July 1999; received in revised form 24 September 1999; accepted 27 September 1999 Abstract The separation of seven pesticides by micellar electrokinetic capillary chromatography in spiked water samples is 21 described, allowing the analysis of pesticides mixtures down to a concentration of 50 mgl in less than 13 min. Calibration, pre-concentration, elution and injection into the sample vial was carried out automatically by a continuous flow system (CFS) coupled to a capillary electrophoresis system via a programmable arm. The whole system was electronically coupled by a micro-processor and completely controlled by a computer. A C solid-phase mini-column was used for the 18 pre-concentration, allowing a 12-fold enrichment (as an average value) of the pesticides from fortified water samples. Under the optimal extraction conditions, recoveries between 90 and 114% for most of the pesticides were obtained.  2000 Elsevier Science B.V. All rights reserved. Keywords: Environmental analysis; Water analysis; Automation; Pesticides 1. Introduction Although gas chromatography (GC) and high-per- formance liquid chromatography (HPLC) are the two Pesticides are important and diverse environmental most commonly used approaches for the analysis of and agricultural species. Their determination in pesticides [2,3], CE is capable of determining pes- pesticides formulations, in feed and food, and in ticides at trace levels as those usually encountered in complex environmental matrices (e.g., water, soil, environmental samples by combining selective pre- sludge, sediments, etc.) often requires a separation column derivatisation schemes, sensitive detection method of high efficiency, unique selectivity and methods (e.g., laser-induced fluorescence detection) high sensitivity [1]. Capillary electrophoresis (CE) and trace enrichment techniques [4]. With the excep- meets these requirement and has proved to be a tion of CE–laser-induced fluorescence detection, the suitable microseparation technique for the analysis of concentration limit of detection of CE is relatively a wide variety of chiral and achiral pesticides. high, a fact that hinders its use in the determination of pesticides at trace levels. However, the combina- tion of on-line and off-line concentration procedures with selective precolumn derivatisation schemes has *Corresponding author. Tel.: 134-957-218-614; fax: 134-957- solved the problem of detectability and allowed CE 218-606. ´ E-mail address: qalmeobj@lucano.uco.es (M. Valcarcel) to become one of the most suitable techniques for the 0021-9673 / 00 / $ – see front matter  2000 Elsevier Science B.V. All rights reserved. PII: S0021-9673(99)01035-3