Development of surfactant based electrochemical sensor for the trace level detection of mercury Anum Zahid a , Aref Lashin b,c , Usman Ali Rana d , Nassir Al-Arifi e , Imdad Ullah a , Dionysios D. Dionysiou f, *, Rumana Qureshi a , Amir Waseem a , Heinz-Bernhard Kraatz g , Afzal Shah a,g, * a Department of Chemistry, Quaid-i-Azam University, 45320 Islamabad, Pakistan b King Saud University, College of Engineering, Petroleum and Gas Engineering Department, P.O. Box 800, Riyadh 11421, Saudi Arabia c Benha University, Faculty of Science, Geology Department, P.O. Box 13518, Benha, Egypt d Sustainable Energy Technologies Centre, PO-box-800, King Saud University, Riyadh 11421, Saudi Arabia e King Saud University, College of Science, Geology and Geophysics Department, P.O. Box 2455, Riyadh 11451, Saudi Arabia f Environmental Engineering and Science Program, Department of Biomedical, Chemical and Environmental Engineering, University of Cincinnati, Cincinnati, OH 45221-0012, USA g Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, M1C 1A4, Canada A R T I C L E I N F O Article history: Received 26 October 2015 Received in revised form 10 December 2015 Accepted 24 December 2015 Available online 28 December 2015 Keywords: Sensor surfactant Hg (II) detection Electro-catalytic effect Computational study A B S T R A C T A highly sensitive electrochemical sensor based on immobilization of a newly synthesized urea functionality containing surfactant, 1-(2, 4-dinitrophenyl)-dodecanoylthiourea (DAN), possessing soil fertility enhancing characteristics, was developed for the detection of Hg(II) using cyclic, square wave and differential pulse voltammetry. Under suitable experimental conditions, calibration plot with a good linearity up to 2 mg/L was obtained with a detection limit of 0.64 mg/L and sensitivity of 0.164 mAL/mg in doubly distilled water at accumulation time of 360 sec using square wave voltammetry. The proposed method was also used for the determination of Hg (II) in drinking and tap water samples with very good recovery data and relative standard deviation of less than 3.5%. The designed sensor exhibited remarkable electro-catalytic effect by dramatically boosting the signal of the analyte as compared to the bare electrode. Computational studies of the interaction of DAN and mercury were also performed. The theoretical results were found in good agreement with the experimental findings. ã 2015 Elsevier Ltd. All rights reserved. 1. Introduction Mercury is one of the most toxic elements [1,2] and its release to the environment has been documented to cause severe health problems such as hearing loss, respiratory tract damage, kidney failure, speech impairment, autism, and vestibular dysfunction [3–6]. The US Environmental Protection Agency (EPA) and World Health Organization (WHO) have declared mercury as a highly toxic element due to its accumulative tendency in soil and atmosphere [7–9]. The adverse effects of mercury on human health and other living organisms have compelled the scientific commu- nity to develop specific and sensitive analytical methods for its trace level detection [10]. In this perspective, we have developed an ultra-sensitive electrochemical sensor based on a soil friendly surfactant for Hg (II) detection with promising results. Remedia- tion technology using environmentally friendly surfactants is of utmost importance due to its nontoxicity, efficient toxin removal ability and compliance with the principles of “green chemistry. Various analytical techniques such as florescence spectrometry, UV–vis spectrophotometry, inductively coupled plasma and mass spectroscopy have been used for the detection of mercury [11–13]. However, electrochemical methods are reliable, fast, able to detect minute amounts of toxins and less expensive as compared to other methods [13–19]. Therefore, we have used electrochemical methods mainly pulse voltammetry for the sensing of mercury on surfactant coated glassy carbon electrode. Modified glassy carbon electrodes are regularly used in pulse voltammetry owing to their simplicity, low cost, reproducibility and low background currents [20–22]. Moreover, pulse voltammetry is associated with favorable signal to noise ratio that makes it effective tool for the determination of target analytes [6,23]. From the past few years modified electrodes have been extensively used because of their tremendous applications in * Corresponding authors. E-mail addresses: dionysios.d.dionysiou@uc.edu (D.D. Dionysiou), afzal.shah@utoronto.ca, afzals_qau@yahoo.com (A. Shah). http://dx.doi.org/10.1016/j.electacta.2015.12.164 0013-4686/ ã 2015 Elsevier Ltd. All rights reserved. Electrochimica Acta 190 (2016) 1007–1014 Contents lists available at ScienceDirect Electrochimica Acta journa l home page : www.e lsevier.com/loca te/ele cta cta