Comparative Methods for Online Preconcentration of Copper Ions on Epichlorohydrin Cross Linked Silica Gel-chitosan Composite Beads and Epichlorohydrin Crosslinked Multi Walled Carbon Nanotube-Chitosan Composite Beads by Flow Injection System

In this work, two different adsorbents were comparatively used and developed for preconcentration of ultra-trace levels of copper ions by flow injection analysis for atomic absorption spectrometry. Copper ions were preconcentrated on a mini-column packed with epichlorohydrin cross-linked silica gel-chitosan composite beads and epichlorohydrin cross linked multiwalled carbon nanotube-chitosan composite beads. 0.1 M ethylene diamine tetra acetic acid and 0.1 M nitric acid solutions were used in order to remove the copper ions from the adsorbents. The factors affecting preconcentration of copper(II) ions such as sample and eluent flow rate, loading time, pH, eluent concentration, and interfering ions were investigated. Under the optimized parameters, detection limits of the methods were obtained as 2 ng ml-1 for epichlorohydrin cross linked silica gel-chitosan composite beads and 1.3 ng ml-1 for epichlorohydrin cross linked multiwalled carbon nanotube-chitosan composite beads with enrichment factor of 23 and 19.2, respectively. The recoveries and intra-day and inter-day precisions for copper ions were >90.0% and >3%, respectively. In order to validate the developed methods, a certified reference material of drinking water was analyzed. The values determined were in good agreement with the certified values. The developed methods have also been applied for determination of copper(II) ions in Gediz River in Turkey with satisfactory results.