Analytica Chimica Acta 579 (2006) 68–73 Synthesis of salicylaldehyde-modified mesoporous silica and its application as a new sorbent for separation, preconcentration and determination of uranium by inductively coupled plasma atomic emission spectrometry Mohammad Reza Jamali a , Yaghoub Assadi b,∗ , Farzaneh Shemirani a , Mohammad Reza Milani Hosseini b , Reyhaneh Rahnama Kozani a , Majid Masteri-Farahani a , Masoud Salavati-Niasari c a School of Chemistry, University College of Science, University of Tehran, Tehran, Iran b Department of Analytical Chemistry, Faculty of Chemistry, Iran University of Science and Technology, Tehran, Iran c Department of Chemistry, Faculty of Science, University of Kashan, Kashan, Iran Received 12 March 2006; received in revised form 3 July 2006; accepted 5 July 2006 Available online 8 July 2006 Abstract A new functionalized mesoporous silica (MCM-41) using salicylaldehyde was utilized for the separation, preconcentration and determination of uranium in natural water by inductively coupled plasma atomic emission spectrometry (ICP-AES). Experimental conditions for effective adsorption of trace levels of U(VI) were optimized. The preconcentration factor was 100 (1.0mL of elution for a 100 mL sample volume). The analytical curve was linear in the range 2–1000 gL -1 and the detection limit was 0.5 ng mL -1 . The relative standard deviation (R.S.D.) under optimum conditions was 2.5% (n = 10). Common coexisting ions did not interfere with the separation and determination of uranium at pH 5. The sorbent exhibited excellent stability and its sorption capacity under optimum conditions has been found to be 10 mg of uranium per gram of sorbent. The method was applied for the recovery and determination of uranium in different water samples. © 2006 Elsevier B.V. All rights reserved. Keywords: Preconcentration; Determination of uranium; Mesoporous silica; Salicylaldehyde; Inductively coupled plasma atomic emission spectrometry 1. Introduction The intense current interest in uranium arises from its known severe exposure to uranium compounds can cause acute renal failure; uranium is also known to induce minor damages to the liver [1]. Uranium exposure increases the risk of getting cancer due to its radioactivity. Since uranium tends to concentrate in specific locations in the body, the risk of bone cancer, liver can- cer, and blood disease increases. It should be noted that uranium is a chemically toxic as being radioactive, the safety profiles for uranium compounds are well stabilized [2,3]. Because uranium is a relatively mobile element in many sur- face or near-surface environments, its geochemical exploration methods require the measurement of the trace quantities of metal ∗ Corresponding author. Tel.: +98 21 77491204; fax: +98 21 77491204. E-mail address: y assadi@iust.ac.ir (Y. Assadi). ion in water samples [4,5] along with that in plants, soils and rocks. The WHO, Health Canada and Australian drinking water guidelines fixed the maximum uranium concentration in drink- ing waters to be less than 9, 20 and 20 gL -1 [6]. This extreme dilution in the presence of relatively high concentrations of other ions makes it difficult to be measured directly and refined analyt- ical methods must be employed to detect small concentrations. Several techniques have been developed for the determina- tion of uranium including -spectrometry [7], neutron activation [8], spectrophotometry [9], molecular fluorescence spectrom- etry [10], gas chromatography [11] and inductively coupled plasma spectrometry [12]. These methods are not sufficiently sensitive for the direct determination of uranium; so that a pre- concentration stage is necessary [6]. Liquid–Liquid extraction of uranium with organic solutions of tri-n-octylphosphine oxide [13], bis(1-phenyl-3-methyl-4- acylpyrazol-5-one) derivatives [14], tri-n-octylamine [15] or 0003-2670/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.aca.2006.07.006