Membrane extraction is a widely employed technique for improving the sensitivity and/or selectivity of a chemical analysis. This paper reports a study on the membrane extraction of aqueous transition metal ions using commercially available Nafion gas dryer assemblies. Though designed and marketed for use with gaseous mixtures, results of this work indicate such assemblies can be effective for the selective extraction of aqueous mixtures after a simple pretreatment procedure not requiring physical modification of the unit. The analytical merit of this sampling approach was evaluated by examining various performance characteristics using aqueous Cu (II) as a model system
