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Solid phase speciation of arsenic by sequential extraction in standard reference materials and industrially
Samuel Van Herreweghe1, Rudy Swennen, Carlo Vandecasteele
1Physico-Chemical Geology, K.U. Leuven, Celestijnenlaan 200C, B-3001 Heverlee, Belgium. samuel.vanherreweghe@postbox.be
Environmental Pollution (Barking, Essex : 1987)
|January 28, 2003
Summary
Sequential extraction methods determine metal speciation, crucial for understanding contaminant risks. NaOH extraction effectively released arsenic from contaminated soils, though heterogeneity impacted results.
Area of Science:
- Environmental Chemistry
- Geochemistry
- Analytical Chemistry
Background:
- Element speciation significantly influences contaminant bioavailability, mobility, toxicity, and risk.
- Sequential extraction is a common method for determining solid-phase speciation of heavy metals when direct compound determination is challenging.
Purpose of the Study:
- To evaluate and compare sequential extraction schemes for heavy metal and arsenic speciation.
- To assess the suitability of standard reference materials (SRMs) for method validation.
- To develop improved extraction schemes for arsenic fractionation.
Main Methods:
- Application of the BCR three-step sequential extraction scheme.
- Implementation of two phosphorus-like extraction schemes based on Manful's protocol.
- Analysis of four SRMs and industrially contaminated soil samples.
Main Results:
- SRM 2710 (Montana soil) proved effective for metal fractionation (Mn, Cu, Zn, As, Cd, Pb) using the BCR scheme.
- Developed arsenic extraction schemes showed potential for better fractionation and recovery than the BCR scheme in SRMs.
- The majority of arsenic in heavily contaminated samples was released by NaOH extraction.
Conclusions:
- Sequential extraction is vital for assessing metal speciation and associated environmental risks.
- SRM 2710 is a suitable reference material for metal fractionation studies.
- NaOH extraction is effective for arsenic release from contaminated matrices, but subsample heterogeneity can affect extraction variability and recovery.