Trace metal analysis: selective sample (copper II) enrichment on an AlgaSORB column

A new approach to sample enrichment for copper(II) determination at trace level is reported. The silica-immobilised cationic polyelectrolyte, [poly (N-xylene-N,N' dicyclohexyl ethylenediamine dibromide)], capable of electrostatic binding with the biofilm of a natural alga Spirogyras sp is used in column separation for enrichment of trace analyte for accurate detection by differential pulse anodic stripping voltammetry. Algae-silica preparation termed as AlgaSORB-sp involves the molecular-level polymer coating as 'spacer' between algae and silica gel. This enables the entire algal film to be accessible for metal uptake and prevents the trace analytes becoming entrapped into the inner-core of the macroporous silica gel. The unique Cu2+ ion-selectivity from multi-elemental complex matrices circumvents the usual problems of overlapping peaks and intermetallic effects. Effects of flow rate, pH, equilibration time and other variables are reported. The system has attractive features for application in single-column ion-chromatography with high durability, simplicity and economy. (C) 2000 Elsevier Science Ltd. All rights reserved.