Dynamic fractionation of trace metals in soil and sediment samples using rotating coiled column extraction and...

Area of Science:

• Environmental Chemistry
• Analytical Chemistry
• Geochemistry

Background:

• Conventional equilibrium-based sequential extraction procedures (SEPs) are time-consuming for partitioning trace elements (TE) in solid samples.
• Dynamic fractionation offers a more efficient alternative for TE analysis in environmental matrices.
• Harmonization of novel dynamic fractionation techniques is crucial for reliable environmental assessments.

Purpose of the Study:

• To harmonize two novel flow-through dynamic fractionation methods: sequential injection microcolumn (SIMC) and rotating coiled column (RCC) extraction.
• To compare the effectiveness of SIMC and RCC for partitioning trace elements (Cu, Pb, Zn) in environmental solid samples.
• To identify critical parameters influencing the reliable assessment of mobilizable trace element pools.

Main Methods:

• Developed and applied SIMC extraction, where the sample is packed in a column within a sequential injection system.
• Developed and applied RCC extraction, retaining particulate matter via centrifugal forces.
• Utilized a five-step sequential extraction procedure with continuous leachant flow (1.0 mL min⁻¹) for partitioning TE in certified reference materials and real soil samples, followed by ICP-AES analysis.

Main Results:

• Both SIMC and RCC demonstrated similar trends in trace element distribution across different fractions.
• Critical parameters for reliable mobilizable TE assessment include particle size-distribution, density, organic matter content, and major element concentration.
• RCC extraction yielded slightly higher recoveries for environmentally relevant TE fractions in reference materials and organic-rich soils, while SIMC was more effective for calcareous soils.

Conclusions:

• SIMC and RCC extraction are viable dynamic alternatives to conventional SEPs for trace element partitioning.
• The choice between SIMC and RCC may depend on soil properties, with RCC showing advantages for organic-rich samples and SIMC for calcareous soils.
• Understanding critical parameters is essential for accurate assessment of mobilizable trace elements in environmental risk evaluations.