TITLE

A novel dynamic approach for automatic microsampling and continuous monitoring of metal ion release from soils exploiting a dedicated flow-through microdialyser

AUTHOR(S)
Miró, Manuel; Jimoh, Modupe; Frenzel, Wolfgang
PUB. DATE
May 2005
SOURCE
Analytical & Bioanalytical Chemistry;May2005, Vol. 382 Issue 2, p396
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
In this paper, a novel concept is presented for automatic microsampling and continuous monitoring of metal ions in soils with minimum disturbance of the sampling site. It involves a hollow-fiber microdialyser that is implanted in the soil body as a miniaturized sensing device. The idea behind microdialysis in this application is to mimic the function of a passive sampler to predict the actual, rather than potential, mobility and bioavailability of metal traces. Although almost quantitative dialysis recoveries were obtained for lead (≥ 98%) from aqueous model solutions with sufficiently long capillaries ( l ≥30 mm, 200 μm i.d.) at perfusion rates of 2.0 μL min−1, the resistance of an inert soil matrix was found to reduce metal uptake by 30%. Preliminary investigation of the potential of the microdialysis analyser for risk assessment of soil pollution, and for metal partitioning studies, were performed by implanting the dedicated probe in a laboratory-made soil column and hyphenating it with electrothermal atomic absorption spectrometry (ETAAS), so that minute, well-defined volumes of clean microdialysates were injected on-line into the graphite furnace. A noteworthy feature of the implanted microdialysis-based device is the capability to follow the kinetics of metal release under simulated natural scenarios or anthropogenic actions. An ancillary flow set-up was arranged in such a way that a continuous flow of leaching solution — mild extractant (10−2 mol L−1 CaCl2), acidic solution (10−3 mol L−1 HNO3), or chelating agent (10−4 or 10−2 mol L−1 EDTA) — was maintained through the soil body, while the concentration trends of inorganic (un-bound) metal species at the soil-liquid interface could be monitored at near real-time. Hence, relevant qualitative and quantitative information about the various mobile fractions is obtained, and metal-soil phase associations can also be elucidated. Finally, stimulus-response schemes adapted from neurochemical applications and pharmacokinetic studies are to be extended to soil research as an alternative means of local monitoring of extraction processes after induction of a chemical change in the outer boundary of the permselective dialysis membrane.
ACCESSION #
17252637

 

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