RESEARCH ARTICLE Copyright © 2010 American Scientific Publishers All rights reserved Printed in the United States of America SENSOR LETTERS Vol. 8, 1–6, 2010 Selective Recognition of Mercury in Waste Water Based on Fluorescence Enhancement Chemosensor M. Hosseini 1 ∗ , Z. Vaezi 2 , M. R. Ganjali 3 4 , F. Faridbod 4 , S. Dehghan Abkenar 1 , and M. Salavati-Niasari 5 1 Department of Chemistry, Islamic Azad University, Savadkooh Branch, Savadkooh, Iran 2 Department of Chemistry, Islamic Azad University, Shahr-e-ray Branch, Iran 3 Center of Excellence in Electrochemistry, Faculty of Chemistry, University of Tehran, Tehran, Iran 4 Endocrinology and Metabolism Research Center, Tehran University of Medical Sciences, Tehran, Iran 5 Department of Chemistry, Faculty of Science, University of Kashan, Kashan, Iran (Received: 18 March 2010. Accepted: 24 May 2010) Fluorescence enhancement of N,N-bis(salicylidene)-naphthylene-1,8-diamine (L) has been used to detect trace amounts of mercury ion in ethanol–water solution. The fluorescent emission intensity of the probe enhances upon binding to mercury ions. The fluorescence enhancement of L is attributed to a 1:1 complex formation between L and Hg 2+ ion. This phenomenon has been utilized as the basis for selective detection of Hg 2+ ion. The chemosensor can be applied for the quantification of Hg 2+ ion in linear range of 16 × 10 −7 to 10 × 10 −5 M. The limit of detection was 13 × 10 −7 M. The sensor exhibits high selectivity toward Hg 2+ ion in comparison with common metal ions. The proposed fluorescent sensor was successfully used for determination of mercury in water and waste water samples. Keywords: Fluorescent Sensor, Mercury, Fluorescence Enhancement Method, Fluorescence. 1. INTRODUCTION Mercury is a highly reactive toxic agent which is difficult to identify its specific mechanism of damage. It damages the central nervous system, endocrine system, kidneys, and other organs, and adversely affects the mouth, gums, and teeth. 1 Exposure over long periods of time or heavy exposure to mercury vapor can result in brain damage and ultimately death. Mercury and its compounds are par- ticularly toxic to fetuses and infants. 1 Women who have been exposed to mercury in pregnancy have sometimes given birth to children with serious birth defects mercury exposure in young children can have severe neurologi- cal consequences, preventing nerve sheaths from forming properly. Mercury inhibits the formation of myelin. There is some evidence that mercury poisoning may predispose to Young’s syndrome. 1 Mercury poisoning’s effects par- tially depend on whether it has been caused by expo- sure to elemental mercury, inorganic mercury compounds (as salts), or organomercury compounds. 2 3 Thus, mercury pollution is a topic of recent concern and has sparked ∗ Corresponding author; E-mail: smhosseini@khayam.ut.ac.ir interest in the design of new chemical tools and tactics for its detection. In the past two decades, an increas- ing interest has been focused on the development of fluorescent sensors, which offer distinct advantages in terms of sensitivity, selectivity, response time and remote sensing. 4–12 A number of highly selective and sensitive fluores- cent chemosensors have been extensively exploited for the detection of Hg 2+ ion in solution; 13–23 however, they have several limitations such as low water solubility, poor selec- tivity toward other metal ions, and weak sensitivity in physiological conditions. Moreover, Hg 2+ ion often causes a turn-off fluorescence response due to the heavy atom or spin-orbit coupling effect. Therefore, the exploration of new fluorescent turn-on probes for analyzing Hg 2+ ion in vivo with appropriate selectivity, high sensitivity, rapid response, and good water solubility remains a challenge. We have recently reported a number of highly selec- tive and sensitive fluorescent sensors for some ions. 24–30 In this study, a highly selective fluorescent sensor for deter- mination of Hg 2+ ions in a wide concentration range is introduced. Sensor Lett. 2010, Vol. 8, No. 6 1546-198X/2010/8/001/006 doi:10.1166/sl.2010.1349 1