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 f r o m sample volumes of u p to several hundred millilitres can be eluted by 5 ml of 2 M nitric acid. It is therefore possible t o achieve pre-concentration factors of up t o 100. In contrast t o FIA methods all ICP-A€ spectrometers can be used for the measurements. Four different chelating ion-exchange materials, Chelex 100, oxine cellulose, CPPl resin and Hyphan cellulose, were compared. Trace elements were enriched from concentrated salt solutions and from NBS standard reference materials following decomposition i n the High Pressure Asher. After elution the elements were measured b y ICP-AES (Plasma II) and b y graphite furnace AAS (HGA-500/Zeeman 5000). Under the conditions tested, Chelex 100, the oxine cellulose and the CPPl resin can be employed satisfactorily i n the automated pre-concentration of a number of elements.

Chelation ion chromatography as a method for trace elemental analysis in complex environmental and biological samples

“…All of these previous methods used an iminodiacetate chelating functionality covalently bonded to a styrene-divinylbenzene polymer that was only slightly cross-linked (1.5-2%), causing the resin to shrink and swell up to 50% of its volume with various pH and ion forms. This makes it difficult to control the resin physically and to use it as a packed column as many papers have described (2,16,20,21). The adjustment of pH, resin size, and flow rate to compensate for the size dynamics of the resin has resulted in variable recoveries of analytes and has been less than satisfactory (15,(21)(22)(23).…”

Application of ICP–OES Techniques in Environmental QC

“…It has been the arrival of flow injection techniques that has revolutionised pre-concentration [36 -391 and automated accessories are now available [40,411. Typically the number of elements that can be extracted simultaneously is between 5 and 10.…”

The role of flow injection analysis within the framework of an automated laboratory

“…Several areas have been identified where it can provide a good, reliable and unique approach. For example Knapp et al [30], Bysouth et al [31] and Cox and McLeod [32] have used the technology to provide simple and effective sample introduction systems in atomic spectroscopy and related techniques. These often yield concentration improvements of 50 times, as well as other advantages.…”