Talanta 81 (2010) 1772–1780 Contents lists available at ScienceDirect Talanta journal homepage: www.elsevier.com/locate/talanta Characterization of a novel chelating resin of enhanced hydrophilicity and its analytical utility for preconcentration of trace metal ions Aminul Islam ∗ , Mohammad Asaduddin Laskar, Akil Ahmad Department of Chemistry, Aligarh Muslim University, Aligarh 202 002, India article info Article history: Received 9 January 2010 Received in revised form 18 March 2010 Accepted 19 March 2010 Available online 25 March 2010 Keywords: Chelating resin p-Hydroxybenzoic acid Sorption behavior Trace metal ions Solid phase extraction abstract A stable extractor of metal ions was synthesized through azo linking of p-hydroxybenzoic acid with Amberlite XAD-4 and was characterized by elemental analyses, infrared spectral and thermal studies. Its water regain value and hydrogen ion capacity were found to be 15.80 and 7.52 mmol g -1 , respectively. Both batch and column methods were employed to study the sorption behavior for the metal ions which were subsequently determined by flame atomic absorption spectrophotometry. The optimum pH range for Co(II), Ni(II), Cu(II), Zn(II), and Pb(II) ions were 10.0, 8.0–9.0, 7.0, 7.0–8.0 and 7.0–8.0, respectively. The half-loading time, t 1/2 , are 6.0, 8.0, 8.0, 8.0 and 4.0 min, respectively. Comparison of breakthrough and overall capacities of the metals ascertains the high degree of column utilization (>75%). The break- through capacities for Co(II), Ni(II), Cu(II), Zn(II), and Pb(II) ions were found to be 0.46, 0.43, 0.42, 0.09 and 0.06 mmol g -1 with the corresponding preconcentration factor of 460, 460, 460, 360 and 260, respec- tively. The limit of preconcentration was in the range of 4.3–7.6 gL -1 . The detection limit for Co(II), Ni(II), Cu(II), Zn(II) and Pb(II) were found to be 0.47, 0.45, 0.50, 0.80, and 1.37 gL -1 , respectively. The Student’s t (t-test) values for the analysis of standard reference materials were found to be less than the critical Student’s t values at 95% confidence level. The AXAD-4-HBA has been successfully applied for the analysis of natural water, multivitamin formulation, infant milk substitute, hydrogenated oil and fish. © 2010 Elsevier B.V. All rights reserved. 1. Introduction Significant accumulation of toxic metals in the environment and their persistent nature have been the subject of great concern in recent years due to their over increased use in various industries [1]. The toxicities of heavy metals may be caused by the inhibition and reduction of various enzymes, complexation with certain lig- ands of amino acids and substitution of essential metal ions from enzymes [2,3]. The indication of their importance relative to other potential hazards is their ranking by the U.S. Agency for Toxic Sub- stances and Disease Registry, which lists all hazards present in the toxic waste sites according to their prevalence and severity of their toxicity. The first, second, third and sixth hazards on the list are heavy metals: lead, mercury, arsenic and cadmium, respectively [4]. Their quantification in industrial effluents, various water resources, environmental and biological samples is important, especially in the environment monitoring and assessment of occupational and environmental exposure to toxic metals. ∗ Corresponding author at: Department of Chemistry, Analytical Research Labo- ratory, Aligarh Muslim University, Aligarh, Uttar Pradesh 202 002, India. Tel.: +91 9358979659. E-mail address: aminulislam.ch@amu.ac.in (A. Islam). Several analytical techniques such as anodic stripping voltam- metry, atomic absorption spectrometry, inductively coupled plasma atomic emission spectrometry and inductively coupled plasma mass spectrometry are available for the determination of trace metals with sufficient sensitivity for most of applications. However, the direct determination of trace metals in real matri- ces is difficult because of the low concentrations of the metals and strong interference from the sample matrix [5,6]. A radical way to eliminate matrix effects is a preliminary separation of macrocomponents by a relative, or absolute, pre- concentration of trace metals. Preconcentration procedures allow one to decrease the detection limits while unifying the analyt- ical schemes for materials of different nature, and simplifying the preparation of calibration samples, as well as improving the reliability of analysis. Therefore, the preconcentration and deter- mination of trace metals in real samples have been a focus in environmental evaluation and protection study. Moreover, precon- centration and separation can lead to a higher confidence level and easy determination of the trace elements by less sensitive, but more accessible instrumentation such as flame atomic absorption spec- trometry (FAAS) [7]. FAAS has been demonstrated [7–9] to be a very effective technique in combination with preconcentration proce- dures. The main advantage of this technique is the possibility of using a relatively simple detection system with flame atomization instead of a flameless technique, which require more expensive 0039-9140/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.talanta.2010.03.035