Rapid immobilisation of 8-hydroxyquinoline onto silica materials and its application for on-line solid-phase extraction of transition metals from environmental samples before ICP-OES monitoring

Chelating resins based on immobilised oxines are attractive solid-phase extraction (SPE) materials
in the analysis of trace metals from environmental samples. The most common immobilisation
procedure for bonding oxines to silica supports is time-consuming and incompatible with “green
chemistry” regulations. In this work, a rapid, environmentally friendly chemical transformation to
attach oxines (i.e. 8-hydroxyquinoline) to silica surfaces is reported. The chelating resin produced by
the procedure described here maintains the chemical configuration (including the spacer arm
separating the reactive groups from the matrix) and is identical to that obtained with the traditional
method. The resin showed satisfactory capacity exchange and excellent performance as a SPE
material for on-line sample preparation (preconcentration and matrix elimination) of some transition
metals before their determination by ICP-OES. The applicability of this SPE material was tested by
analysing Cu, Co, Zn, Ni and Pb in the range of 50-300 ng ml-1 from a synthetic matrix simulating
sediment. The recovery values ranged from 100% for Zn to 70% for Ni. The system was used with
optimised parameters to analyse these ions in different sediment reference materials. The results
showed good agreement with certified values.