title: Demetalisation of soils by continuous acidified subcritical water extraction.
abstract: Acidified subcritical water is proposed for the continuous extraction of metals (namely, lead, copper, cadmium, arsenic, selenium and mercury) from soils prior to: (a) continuous derivatisation (by hydride formation for As and Se, and cold vapour formation for Hg) and determination by atomic fluorescence; and (b) determination by Graphite Furnace-Atomic Absorption Spectrometry for Pb, Cu and Cd. Soil samples (5 g) were subjected to 90-min dynamic extraction with water modified with 4% (v/v) HNO(3) at 200 degrees C and 30 bar. A univariate optimisation of the variables related to derivatisation (for As, Se and Hg) and detection (for all of them), and a multifactorial optimisation of the variables affecting the continuous extraction step were performed. A kinetics study of the extraction process was performed in order to control the lowering of metals in the soil. The method was compared with the EPA-3051 reference method. The good reproducibility of the method, together with its safety and low cost, make it a good alternative for the demetalisation of contaminated soil.
authors.affiliation: Analytical Chemistry Division, University of Córdoba, Annex C-3, Campus of Rabanales, E-14071 Córdoba, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Priego-López
authors.forename: M D
authors.initials: MD
authors.lastname: Luque de Castro