Evaluation of Calcium Alginate Microparticles for Copper Preconcentration prior to F AAS Measurements in Fresh Water

Abstract

A method for separation and preconcentration of Cu2+ from fresh waters prior to flame atomic absorption spectrometry (FAAS) measurements, using calcium alginate (CA) microparticles, is proposed. Off-line analytes preconcentration was achieved using a flow-injection system incorporating a column containing CA (< 180 μm; 300 mg). The preconcentration procedure consisted of 50 mL sample or standard (at pH = 6) loading at 2.0 mL min-1 followed by analyte elution with 3 mL of HCl 1 mol L-1. In these conditions, the enrichment factor was 17 times. The calibration curves were built ranging from 5 to 50 µg L-1 Cu2+. The procedure was applied for the analysis of fresh water sample spiked with 10 µg L-1 Cu2+, resulting in a recovery higher than 94%. Additionally, inter-column reproducibility (RSD < 3,5%; n = 5 columns) and the limit of detection of 0.8 µg L-1 were considered appropriate by taking into the maximum permitted Cu levels by the Brazilian National Environment Council (CONAMA) of 9 µg L-1 (fresh water, Class 1). The proposed approach using CA columns is a reliable and lower cost alternative for single-stage Cu preconcentration prior to F AAS measurements and can be recommended for the analysis of river fresh waters. CA column re-usability was confirmed up to 100 adsorption-desorption cycles.