Effects of capacity on the preconcentration of trace metals and matrix elimination by an iminodiacetate chelating adsorbent

• Low capacity adsorbents, based on iminodiacetic acid and a crosslinked agarose, Novarose(TM), have been synthesised for the enrichment of metal ions. Test ions Cu2+ with high, and Cd2+ with a moderate affinity for the sorbent were selected. The study includes the effect of specific capacity and matrix composition on the rate of uptake and recovery of these ions. Using a column packed with 0.25 ml of a sorbent and a sample volume of 100 ml, Cu2+ is quantitatively accumulated from all of the matrices studied even at a capacity of 6 mu mol ml(-1) of adsorbent and a flow rate as high as 100 ml min(-1). The enrichment of Cd2+ is affected by the matrix and for quantitative recovery the flow rate and capacity must be properly adjusted. In the presence of 0.01 M Ca2+, a specific capacity of 45 mu mol ml(-1) is needed for quantitative retainment and a flow rate of 100 ml min(-1), whereas a capacity of 10 mu mol ml(-1) suffices at 10 ml min(-1). The advantage of low specific capacity on the removal of matrix elements has been demonstrated. A method based on the determination of conditional stability constants of the metal sorbent complex is suggested for predicting the sorbent capacity needed to acquire quantitative recovery and optimal matrix elimination.

Nyckelord

iminodiacetate adsorbent; low capacity; preconcentration; matrix elimination; PLASMA-MASS SPECTROMETRY; NATURAL-WATERS; SEPARATION; SYSTEM; ELEMENTS; RESIN

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