Journal of Hazardous Materials 161 (2009) 641–648 Contents lists available at ScienceDirect Journal of Hazardous Materials journal homepage: www.elsevier.com/locate/jhazmat Perchlorate-selective polymeric membrane electrode based on bis(dibenzoylmethanato)cobalt(II) complex as a neutral carrier Behzad Rezaei ∗ , Soraia Meghdadi, Saeid Bagherpour Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111, Islamic Republic of Iran article info Article history: Received 26 November 2007 Received in revised form 13 February 2008 Accepted 1 April 2008 Available online 6 April 2008 Keywords: Ion-selective electrode Bis(dibenzoylmethanato)cobalt(II) Perchlorate Poly(vinyl chloride) abstract A synthesized bis(dibenzoylmethanato)Co(II) complex (Co(DBM) 2 ), has been used as a ionophore for the preparation of a new perchlorate ion-selective electrode. The electrode exhibits a Nernstian response over the perchlorate concentration range of 8.0 × 10 -7 –1.0 × 10 -1 M with a slope of 60.3 ± 0.5 mV per decade of concentration. The limit of detection as determined from the intersection of the extrapolated linear segments of the calibration plot is 5.6 × 10 -7 M. The electrode shows good selectivity towards perchlorate with respect to many common anions. The response time of the sensor is very fast (≤5 s), and can be used for at least 2 months in the pH range of 2.0–9.0. The electrode was used to determine perchlorate in water and human urine. The interaction of the ionophore with perchlorate ions was demonstrated by UV–vis spectroscopy. © 2008 Elsevier B.V. All rights reserved. 1. Introduction Perchlorate is regarded as a new emerging persistent inorganic contaminant because of its specific properties, such as high water solubility, mobility and considerable stability [1]. One of the major sources of this environmental contamination is the manufacture or improper storage or disposal of ammonium perchlorate which is used as a primary component of solid propellant for rockets, mis- siles, fireworks [2–4], or explosives in various military munitions and air bag inflators [5]. Perchlorate has also been found in food products [6–8], soil [9], milk [10], fertilizers [11], plants [12] and in human urine [13]. The perchlorate and iodide ion have a similar size, therefore can be taken up in place of it by the mammalian thyroid gland. In this way, perchlorate can be affected on the production of thyroid hormones. Moreover, other physiologic systems may be indirectly affected. It is due to the abnormalities in child development and the thyroid cancer. It poses the greatest threat in the drinking water of expectant mothers, children under 12 years and persons with mal- functioning thyroids. Perchlorate ions have also been applied as growth promoters and as thyreostatic drugs in cattle fattening [14]. Thyroid gland tumors were spotted in rodent animals after expo- sure to high dose of perchlorate [15]. The toxicologic mechanisms through which perchlorate exerts its effects have been reviewed in some reports [16–18]. ∗ Corresponding author. Tel.: +98 3113912351; fax: +98 3113912350. E-mail address: rezaei@cc.iut.ac.ir (B. Rezaei). According these findings, several organizations have been iden- tified standard levels for perchlorate. The National Academy of Science’s (NAS’s), in the January 2005, was reported maximum per- missible dose of 0.7 g/kg/day for perchlorate concentration, which correlates to a drinking water equivalent level of 24.5 g/L if drink- ing water is considered as the only source of perchlorate [19]. In February 2005, also the United States Environmental Protection Agency (US EPA) set the 24.5 g/L as an official reference dose (RFD) for perchlorate in drinking water, which is consistent with the RFD recommended by NAS [20]. Therefore, determination of perchlorate ion in various samples such as ground water, propellants, explosives and urine in the presence of other anions is of special importance [21]. The determi- nation of perchlorate ions has been carried out directly or indirectly by a variety of classical and instrumental methods, including volumetric titrations [22], gravimetry [23], spectrophotometry [24], atomic absorption spectrophotometry [25], and chromatog- raphy [14]. These methods also suffer from various interferences. Therefore, a simple, rapid, sensitive and selective method for the determination of perchlorate ion is required. One technique that holds excellent promise as a routine monitoring device is potentio- metric measurement via an ion-selective electrode. It is well known that ISE is one of the few techniques that can measure both positive and negative ions depending on the nature of the ionophore. In fact a number of ion-selective electrodes for target cations and anions have been reported [26]. Potentiometric detection based on ion-selective electrodes (ISEs), as a simple method, has several advantages, such as speed, ease of preparation and procedures, simple instrumentation, fast 0304-3894/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.jhazmat.2008.04.005