Enrichment Procedures for Water Analysis by X-Ray Energy Spectrometry

Abstract

Energy-dispersive X-ray fluorescence might advantageously be used for the determination of trace metals in water. Suspended material can straightforwardly be collected on a 0.45 μm pore-size Nuclepore membrane by filtration. Dissolved ion analysis usually requires a physical or chemical enrichment step. Spotting a 1.5 ml water sample on a Whatman-41 filter within a 29 mm diameter hydrophobic ring and drying by a cold air stream from underneath yielded a 50 ppb sensitivity for many elements, and a 18% accuracy. Filtration of a 200 ml water sample at the natural pH through a pair of Chelest-100 chelating ion-exchange resin loaded filter papers allowed 1-5 ppb sensitivities but suffered from the combination of limited load capacity and significant uptake of usually abundant alkali earth metals.