Talanta 79 (2009) 1197–1203 Contents lists available at ScienceDirect Talanta journal homepage: www.elsevier.com/locate/talanta A novel high selective and sensitive para-nitrophenol voltammetric sensor, based on a molecularly imprinted polymer–carbon paste electrode Taher Alizadeh a,∗ , Mohammad Reza Ganjali b,c , Parviz Norouzi b,c , Mashallah Zare b , Ali Zeraatkar b a Department of Applied Chemistry, Faculty of Science, University of Mohaghegh Ardabili, Ardabil, Iran b Center of Excellence in Electrochemistry, Faculty of Chemistry, University of Tehran, Tehran, Iran c Endocrinology & Metabolism Research Center, Medical Sciences/University of Tehran, Tehran, Iran article info Article history: Received 12 January 2009 Received in revised form 20 February 2009 Accepted 21 February 2009 Available online 9 March 2009 Keywords: Para-nitrophenol Molecularly imprinted polymer Voltammetric sensor Carbon paste electrode abstract By using a molecularly imprinted polymer (MIP) as a recognition element, the design and construction of a high selective voltammetric sensor for para-nitrophenol was formed. Para-nitrophenol selective MIP and a non-imprinted polymer (NIP) were synthesized, and then used for carbon paste (CP) electrode preparation. The MIP–CP electrode showed greater recognition ability in comparison to the NIP–CP. It was shown that electrode washing after para-nitrophenol extraction led to enhanced selectivity, without noticeably decreasing the sensitivity. Some parameters affecting sensor response were optimized and a calibration curve was plotted. A dynamic linear range of 8 × 10 -9 to 5 × 10 -6 mol L -1 was obtained. The detection limit of the sensor was calculated as 3 × 10 -9 mol L -1 . Thus, this sensor was used successfully for the para-nitrophenol determination in different water samples. © 2009 Elsevier B.V. All rights reserved. 1. Introduction Phenol compounds such as nitrophenols are amongst the category of serious environmental contaminants, and their deter- mination in environmental samples has been of high interest due to their toxic effects on humans, animals and plants [1]. Nitroaro- matic compounds can be formed by photochemical atmospheric reactions owing to the presence of nitrogen oxides in industrial and automotive emission gases. They are also widely used in the production of pesticides, paints and explosive materials [2,3]. Nitroaromatic compounds are considered by the United States Envi- ronmental Protection Agency as main pollutants, because they are toxic to human health [4]. In particular, para-nitrophenol is a toxic hydrolysis product of the insecticides parathion and paraoxon, and also exists in wastewater from industries such as refineries. Detox- ification of water contaminated with nitroaromatic compounds is usually a very difficult process since the presence of a nitro-group on the aromatic compound. This confers a strong chemical stabil- ity and resistance of microbial degradation [5]. The detection of para-nitrophenol is important for protecting water resources and food supplies in the defense against terrorist activity, and for mon- itoring detoxification processes [6]. Therefore, there are growing demands for portable devices for reliable on-site monitoring of para-nitrophenol compounds. ∗ Corresponding author. Tel.: +98 451 5514702; fax: +98 451 5514701. E-mail address: taa 55@yahoo.com (T. Alizadeh). Some laboratory-based analytical methods for determin- ing para-nitrophenol compounds such as; gas and liquid chromatography [7–13], UV–vis spectrophotometry [12,13] and spectrofluorimetry [14] have been reported. The use of enzyme- linked immunosorbent assay has also been accounted for [15]. However, for the majority of these methods, some sample pre- treatment involving separation, extraction and adsorption is generally necessary. These can be time-consuming and com- plex. Electrochemical methods, such as differential pulse polarog- raphy, anodic stripping voltammetry and differential pulse voltammetry, have been widely applied for the determination of pharmaceuticals, dyes, insecticides, pesticides and inorganic ions [16–19]. Modified electrodes are being used frequently in the voltammet- ric determination of organic compounds because of their efficiency and the selectivity that can be obtained by varying the modi- fier. In recent years, chemically modified electrodes were used for the voltammetric quantification of various organic and inorganic species after their accumulation [20–22]. Multitudes of modifying agents were used either as coatings on solid electrode surfaces, or dispersed within a conductive matrix. Some modified electrodes have been reported such as: a glass carbon electrode impregnated with a lithium tetracyanoethylenide (LiTCNE) [23], and a sodium montmorillonite-anthraquinone chemically modified glass carbon electrode [6], for the determination of para-nitrophenol. These modifiers have advantages—stability for a long duration of time and simplicity in preparation. However, they suffer from a main 0039-9140/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.talanta.2009.02.051