Analytica Chimica Acta 517 (2004) 71–79 Simultaneous determination of phenyl- and sulfonylurea herbicides in water by solid-phase extraction and liquid chromatography with UV diode array or mass spectrometric detection R. Carabias-Mart´ ınez ∗ , E. Rodr´ ıguez-Gonzalo, E. Herrero-Hernández, J. Hernández-Méndez Departamento de Qu´ ımica Anal´ ıtica, Nutrición y Bromatolog´ ıa, Facultad de Qu´ ımica, Universidad de Salamanca, 37008 Salamanca, Spain Received 29 January 2004; received in revised form 4 May 2004; accepted 4 May 2004 Abstract A method for the simultaneous determination of 10 sulfonyl- and phenylurea herbicides (chlorsulfuron, triasulfuron, fenuron, monuron, flu- ometuron, chlorotoluron, isoproturon, diuron, metobromuron, linuron) and one of their most common degradation products (3-chloro-4-methyl- phenyl urea) has been developed. Liquid chromatography with diode array UV detection (LC–DAD UV) and positive ion electrospray mass spectrometry (LC–ESI–MS) were used for the separation, identification and quantification of these analytes. In the LC–DAD UV method, chromatographic separation was achieved in about 27 min; however, analysis time can be reduced to less than 13 min when LC–MS is applied, since no complete separation of the chromatographic peaks was required. A preconcentration step based on solid-phase extraction was applied for the simultaneous extraction of sulfonylureas (acidic in nature) and phenylureas (neutral compounds) from water samples. Different types of sorbents were evaluated: silica-based C 18 and two polymeric sorbents, Oasis HLB and LiChrolut EN. The best results were obtained with Oasis HLB, a co-polymer of poly(divinylbenzene-co-N-vinylpyrrolidone). Other parameters, such as the elution solvent and sample volume, were optimised in order to maximise extraction efficiency; the recoveries obtained varied between 70 and 95% for the acidic and neutral herbicides extracted jointly without acidification of the sample. Both procedures, SPE LC–DAD UV and SPE–LC–MS, were applied to spiked river waters and were compared in terms of selectivity and sensitivity. The detection limits obtained in river water samples were below 50 ng L -1 for both procedures. © 2004 Elsevier B.V. All rights reserved. Keywords: Water analysis; Liquid chromatography; Diode array UV detection; Mass spectrometry; Solid-phase extraction; Herbicides; Phenylureas; Sulfonylureas 1. Introduction For many years, pesticide analysis in environmental sam- ples has attracted much attention due to the wide use of such compounds in agriculture and household applications, as well as their environmental impact. Herbicides represent about 50% of the demand for agricultural chemicals; their prolonged use involves the risk of their retention in crops and soils, from which—in turn—due to washing and leach- ing processes these substances pass to surface and ground waters [1,2]. This uptake of pesticides into watercourses, to- gether with their transport by the wind and their propagation ∗ Corresponding author. Fax: +34-923-294483. E-mail address: rcm@usal.es (R. Carabias-Mart´ ınez). through biological chains, means that both they and their degradation products must be monitored, not only in the ar- eas where they are applied but also in more or less proximal areas [3,4]. Phenyl- and sulfonylurea herbicides are widely used as selective pre- and post-emergence herbicides for the control of most broad-leaved weeds and annual grasses in many agricultural crops. Phenylurea herbicides are neutral in nature while sulfonylureas are weakly acidic compounds. In recent years, sulfonylurea herbicides have become very popular worldwide because of their low application rates (10–40 g ha -1 ), low toxicity to mammals, and unprece- dented herbicidal activity. Nevertheless, the use of phenyl- and sulfonylureas as agrochemicals to improve crop yields is not without trade- offs. The polar nature of these herbicides and their fairly 0003-2670/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.aca.2004.05.007