TXRF cation analysis by anionic membrane collection

A new method for the determination of trace levels of cationic ions by anion selective membrane collection is presented. Anion selective membranes containing a few micrograms of different complexing reagents in polyvinyl chloride (PVC) matrix were produced in quartz reflectors. The membranes were immersed in water solutions with low concentrations of cationic metals, Cu, Co, Ni, Zn, and of anionic ligands (CN - , etc.). After the equilibration time the reflectors were left to dry and they were analyzed by Total X-Ray Fluorescence (TXRF). Many experimental parameters (pH effect, size of the membrane, volume sample) were examined. The minimum detection limits were estimated to be 1 ng/ml for all metallic cations even in seawater. The method needs less working labor than other enrichment procedures, the cations are collected directly on the TXRF reflector surface and very small chemical reagent consumption is needed.