An on-line continuous flow system for copper enrichment and determination by flame atomic absorption spectroscopy

An on-line enrichment flow system has been developed in order to determine trace amounts of copper in seawater and biological samples. It is based on the chemical sorption of copper(II) ions onto a minicolumn packed with Amberlite XAD-2 resin loaded with calmagite reagent. After copper preconcentration, it was eluted by 1 mol l(-1) hydrochloric acid solution and determined directly by flame atomic absorption spectrometry (FAAS). A preconcentration factor of 32 in 13.5 ml of sample (3 min preconcentration time) was achieved by using the time-based technique. The detection limit (3 sigma) was 0.15 mu g l(-1) and the precision (assessed as the relative standard deviation) reached values within the range of 2.7-6.0% in copper solutions varying from 0.0 to 20 mu g l(-1) concentration, respectively. Chemical and flow variables as well as concomitant were studied in the developed procedure. The method was tolerant to other ions usually present in the analyzed samples. The proposed procedure was successfully applied to determine copper in biological certified reference material. Achieved recoveries of copper in samples of seawater and biological material, measured by standard addition technique proved also that the proposed procedure has a good accuracy. (C) 2000 Elsevier Science B.V. All rights reserved.