Cation-exchange behaviour of a range of adsorbents and chromatographic supports with regard to their suitability for investigating trace metal speciation in natural waters

Abstract

The adsorption of simple cations of iron, copper zinc and magnesium by a range of adsorbents and chromatographic supports has been investigated using an atomic fluorescence detector directly coupled to a liquid chromatograph. The crosslinked polyaromatic resins (XAD-2, Chromosorb 101 and 102, Porapak P, PS, Q and QS and Benson BN-X4 and BN-X10) all act as cation-exchange resins with capacities of about 0.1–0.5 μequiv. g −. Octadecyl-bonded silica has a similar capacity provided care is taken to ensure that no alkylgroups are hydrolysed from the surface. Activated charcoal and the polyacrylic ester resins, XAD-7 and XAD-8, have ion-exchange capacities that are higher by one to two orders of magnitude. These cation-exchange capacities, although low, must be taken into account if these resins are used to study trace metal speciation in natural waters.