Preconcentration and Separation of Metal Ions Using a Pyridazine Derivative Immobilized Glass Beads

Abstract

We synthesized a metal chelating sorbent by immobilizing a pyridazine derivative on glass beads and investigated the adsorption and separation behavior of the beads for metal ions. The beads were synthesized by reacting glass beads (amino-aryl-CPG) with 3-chloropyridazine-6-carboxylic acid hydrazide in toluene at 110° C for 12 h. The exchange capacity of the beads for copper determined by a batch method was about 0.1 mmol g-' (glass beads). The beads reacted with various metal ions in several solutions of differing pH, and the degree to which the metal ions coordinated to the pyridazine derivative was indicated by a color change. Using a column method, metal ions were selectively retained, and then quantitatively and separately eluted from the beads by a stepwise elution employing several eluents, including hydrochloric acid. A column packed with the beads was successfully used to determine trace metal ions in both tap-and rain-water samples. KeywordsTrace metal ion, preconcentration, pyridazine derivative immobilized glass beads, tap water, rain waterIn general, the metals contained in waste streams are a serious source of environmental pollution. Metals are also both essential and toxic to biologically important reactions. Accordingly, routine analysis and the continuing development of new methods to determine metals are of significant importance. Trace analysis is particularly important, since the metal concentrations in many biological and environmental samples, including wastewater, are very low. However, the lack of selectivity of the determination methods means that the metal concentrations in samples are often below the detection limits, and/or the coexisting components often interfere. As a result, direct analysis can't usually be carried out. In such cases, a pretreatment (preconcentration of the trace metals and/or separation of interfering matrix matter) is necessary. Typical pretreatment methods include sorption, coprecipitationl, solvent extraction2-4, and ion-exchange.5-8 However, they are often not sufficiently selective, and usually limit the type of analytical methods that can be used and/or are timeconsuming. Recently, the preconcentration of metals using 8-hydroxyquinoline immobilized on an insoluble support has been reported.g-16 Though there is some practical value of this method (re-use of disposable reagents has received with keen interest), there are problems with its low selectivity towards metal ions.Having noticed the application of chelating reagents immobilized sorbents to metal analysis in the literature, we decided to synthesize a pyridazine derivative immobilized glass beads and use it to separate and concentrate trace metal ions from environmental samples, such as tap-and rain-water samples. The Experimental

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