Dinonylnaphthalene sulfonic acid (HD) has been used as a preconcentrating agent to enrich trace metal ions and to separate
the interfering elements such as Na, K, Cl and Br which normally exist in the natural aqueous systems. Experiments were performed
by extracting the ions in the aqueous medium with HD in n-hexane and subsequently back-extracted into a minimal volume of
acid solution. Factors influencing the extraction efficiency of the ions of interest were investigated. The preconcentration
technique developed in this study was applied to the determination of trace elements in biological and natural water samples
by neutron activation analysis.