Synthesis and application of an inert type of 8-hydroxyquinoline-based chelating ion exchanger for sea-water analysis using on-line inductively coupled plasma mass spectrometry detection

Abstract

An inert type of chelating ion exchanger is prepared by Friedel–Crafts alkylation of 8-hydroxyquinoline (8-HQ) with a previously chloromethylated poly(styrene)–divinylbenzene (PS/DVB) co-polymer. This type of Friedel–Crafts alkylation using a polymer alkylhalogenid results in an exchange capacity of 2.8 µmol Cu²⁺ per ml of bed volume. Because of the high formation constants of most transition and heavy metal ion complexes with 8-HQ, the low exchange capacity is still sufficient to preconcentrate a wide variety of ions from a high ionic strength sample such as sea-water. The introduction of a high-performance cation-exchange column into the elution flowpath enhanced the selectivity of the method significantly. From an initial set of 32 elements it is possible to preconcentrate 25 elements with a recovery of at least 50%. The majority of trace elements show a recovery of 60–90%. The introduction of a cation-exchange column into the elution flow path allowed the elimination of several remaining interferences. The basic performance, such as recovery and elution behaviour, as well as first results of applied analysis of sea-water using the Nearshore Seawater Reference Material for Trace Metals, CASS-2 (National Research Council of Canada) are given. The on-line detection using inductively coupled plasma mass spectrometry allows trace analysis at the low ng l^–1 range in sea-water, which is the normal concentration level for most of the trace elements.