Field sample preconcentration of copper in sea water using chelating minicolumns subsequently incorporated on a flow-injection–flame atomic absorption spectrometry system

Abstract

A field flow preconcentration system for copper determination in seawater is described. Seawater samples are collected and preconcentrated in situ by passing them using a peristaltic pump through a minicolumn packed with Amberlite XAD-4 impregnated with the complexing agent 1-(2-pyridylazo)-2-naphthol. Thus, copper is preconcentrated without the interference of the saline matrix. Once in the laboratory, the minicolumns loaded with copper are incorporated on a flow injection system and eluted with a small volume of a 20% (v/v) ethanolic solution of 0.5 mol L⁻¹ hydrochloric acid into the nebuliser–burner system of a flame atomic absorption spectrometer. The analytical figures of merit for the determination of copper are as follows: detection limit (3s), 0.06 μg L⁻¹; precision (RSD), 1.2% for 2 μg L⁻¹; enrichment factor, 30 (using 25 mL of sample and 83 μL of eluent). Analysis of certified reference materials (SLEW-3 and NASS-5) showed good agreement with the certified value. This procedure was applied to the determination of copper in seawater samples from Galicia (Spain).