Highly integrated flow assembly for automated dynamic extraction and determination of readily bioaccessible chromium(VI) in soils exploiting carbon nanoparticle-based solid-phase extraction

• Published in: Analytical and bioanalytical chemistry Vol. 400; no. 7; pp. 2217 - 2227
• Main Authors: Rosende, María, Miró, Manuel, Segundo, Marcela A., Lima, José L. F. C., Cerdà, Víctor
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.06.2011; Springer
• Subjects: Analytical Chemistry; Automated; Biochemistry; Carbon; Carbon - chemistry; Carbon content; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Chromium; Chromium - chemistry; Exact sciences and technology; Extraction; Food Science; Laboratory Medicine; Leaching; Monitoring/Environmental Analysis; Nanoparticles; Nanostructure; Nanotubes; Original Paper; Soil Pollutants - analysis; Soils; Spectrometric and optical methods; Technology application; Hexavalent chromium; Soil; Automation; Miniaturization; Bioaccessibility test; Carbon nanoparticles; Water; Performance evaluation; Solid phase extraction; Nanoparticle; Carbon nanotubes; Derivatization; Chemical enrichment; Sample preparation; Batchwise; Standard test; Dynamics; Flow injection; Minimization; Method; Carbon; In vitro; Leaching; Uptake; Contamination; Automatic processing; Soils; Dilution; Reference material; Portable equipment; Kinetics; Detection; Spectrophotometry; Leachate; Chromium VI; Packed column
• ISSN: 1618-2642; 1618-2650
• DOI: 10.1007/s00216-011-4954-y

An automated dynamic leaching test integrated in a portable flow-based setup is herein proposed for reliable determination of readily bioaccessible Cr(VI) under worst-case scenarios in soils containing varying levels of contamination. The manifold is devised to accommodate bi-directional flow extraction followed by processing of extracts via either in-line clean-up/preconcentration using multi-walled carbon nanotubes or automatic dilution at will, along with Cr(VI) derivatization and flow-through spectrophotometric detection. The magnitude of readily mobilizable Cr(VI) pools was ascertained by resorting to water extraction as promulgated by current standard leaching tests. The role of carbon nanomaterials for the uptake of Cr(VI) in soil leachates and the configuration of the packed column integrated in the flow manifold were investigated in detail. The analytical performance of the proposed system for in vitro bioaccessibility tests was evaluated in chromium-enriched soils at environmentally relevant levels and in a standard reference soil material (SRM 2701) with a certified value of total hexavalent chromium. The automated method was proven to afford unbiased assessment of water-soluble Cr(VI) in soils as a result of the minimization of the chromium species transformation. By combination of the kinetic leaching profile and a first-order leaching model, the water-soluble Cr(VI) fraction in soils was determined in merely 6 h against >24 h taken in batchwise steady-state standard methods. Schematic representation of the compact flow set-up for automated dynamic extraction and determination of readily bioaccessible Cr(VI) in soils