Journal of Chromatography A, 995 (2003) 233–238 www.elsevier.com / locate / chroma Short communication On-line solid-phase extraction with molecularly imprinted polymers to selectively extract substituted 4-chlorophenols and 4-nitrophenol from water a a b b ´ Ester Caro , Rosa M. Marce , Peter A.G. Cormack , David C. Sherrington , a, * Francesc Borrull a ´ ´ ´ ` Departament de Quımica Analıtica i Quımica Organica, Universitat Rovira i Virgili, Imperial Tarraco 1, 43005 Tarragona, Spain b Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow G11XL, UK Received 19 September 2002; received in revised form 7 March 2003; accepted 25 March 2003 Abstract Three polymers have been synthesised using 4-chlorophenol (4-CP) as the template, following different protocols (non-covalent and semi-covalent) and using different functional co-monomers, 4-vinylpyridine (4-VP) and methacrylic acid (MAA). The polymers were evaluated to check their selectivity as molecularly imprinted polymers (MIPs) in solid-phase extraction (SPE) coupled on-line to liquid chromatography. The solid-phase extraction procedure using MIPs (MISPE), including the clean-up step to remove any interferences, was optimised. The 4-VP non-covalent polymer was the only one which showed a clear imprint effect. This MIP also showed cross-reactivity for the 4-chloro-substituted phenols and for 4-nitrophenol (4-NP) from a mixture containing the 11 priority EPA (Environmental Protection Agency) phenolic compounds and 4-chlorophenol. The MIP was applied to selectively extract the 4-chloro-substituted compounds and 4-NP from river water samples.  2003 Elsevier Science B.V. All rights reserved. Keywords: Water analysis; Solid-phase extraction; Molecular imprinting; 4-Chlorophenols; 4-Nitrophenol 1. Introduction lytes [3–7]. This effect, known as cross-reactivity, is particularly interesting in environmental samples, Molecularly imprinted polymers (MIPs), which since these may contain several structurally related can be prepared by three different protocols [1,2], are compounds. highly crosslinked polymers synthesised in the pres- Nearly all the data published about MIPs as ence of a template molecule. However, in some sorbents in solid-phase extraction (MISPE) has been cases, the MIP recognises not only the template in generated in an off-line mode [4,8–10]. Few applica- the rebinding step but also structurally related ana- tions have been developed using an on-line mode with the MISPE coupled to liquid chromatography (LC) [2,3,11–14] and only some of them have used *Corresponding author. Tel.: 134-977-558-137; fax: 134-977- only one imprinted pre-column [2,12,13], which 559-563. E-mail address: borrull@quimica.urv.es (F. Borrull). offers significant advantages in terms of the ease of 0021-9673 / 03 / $ – see front matter  2003 Elsevier Science B.V. All rights reserved. doi:10.1016 / S0021-9673(03)00543-0