Solid Phase Extraction of Ultra Trace Copper Using Octadecyl Silica Bonded Phase Membrane Disks Modified by a New Symmetric Schiff Base Ionophore Prior to FAAS Determination

Abstract

A very selective, reliable and precise method for rapid separation of the trace amounts of copper in aqueous samples using octadecyl silica bonded phase membrane disks modified by N,N-ethylene-bis-(3-formyl-5-methyl salicyl aldymine) combined with flame atomic absorption spectrometric determination has been established. All the affecting experimental variables such as pH, amount of modifier, eluent type, sample and eluent flow-rate, foreign ions and disk capacity were also investigated. The target analyte (trace copper) was quantitatively retained at pH=4, and eluted with 8 mL of HCl (1M) and HNO3 0.5 M each containing 2.0% (v/v) methanol applying flow rates of 50 mL min-1 and 15 mL min-1 for sample introduction and elution steps, respectively. The proposed method exhibits a wide linear dynamic range over 5- 150 ng mL-1 and reproducibility at the most 3%. It also permits an enrichment factor of about 400 or higher and a detection limit of 0.005 ng mL-1. The method has been successfully applied for isolation and determination of copper in different aqueous, real samples, peppers and standard alloys. Keywords: Copper(II), Flame atomic absorption spectrometry, Modifier, N,N'-ethylene bis-(3-formyl-5-methyl salicyl aldymine) (EFMA), Solid phase extraction, Schiff Base Ionophore, Total reflection X-ray fluorescence (TXRF) spectrometry, Inductively coupled plasma optical emission spectrometry (ICP-OES), Atomic fluorescence spectrometry (AFS), Environmental samples