Automation in element pre-concentration with chelating ion exchangers. Plenary lecture

Abstract

A microprocessor controlled pre-concentration system that permits the automated off-line pre-concentration of several samples at the same time is described. Trace elements pre-concentrated from sample volumes of up to several hundred millilitres can be eluted by 5 ml of 2 M nitric acid. It is therefore possible to achieve pre-concentration factors of up to 100. In contrast to FIA methods all ICP-AE spectrometers can be used for the measurements. Four different chelating ion-exchange materials, Chelex 100, oxine cellulose, CPPI resin and Hyphan cellulose, were compared. Trace elements were enriched from concentrated salt solutions and from NBS standard reference materials following decomposition in the High Pressure Asher. After elution the elements were measured by ICP-AES (Plasma II) and by graphite furnace AAS (HGA-500/Zeeman 5000). Under the conditions tested, Chelex 100, the oxine cellulose and the CPPI resin can be employed satisfactorily in the automated pre-concentration of a number of elements.