Downloaded by NANYANG TECHNOLOGICAL UNIV on June 3, 2016 | http://pubs.acs.org Publication Date: February 14, 2002 | doi: 10.1021/bk-2002-0811.ch006
Chapter 6
Permeation Liquid Membrane Coupled to Voltammetric Detection for In Situ Trace Metal Speciation Studies N. Parthasarathy, P. Salaün, M. Pelletier, and J. Buffle* CABE, Department of Inorganic, Analytical and Applied Chemistry, University of Geneva, SciencesII,30 QuaiΕ.Ansermet, CH-1211 Geneva 4, Switzerland
Permeation liquid membranes (PLM) are emerging as a versatile analytical tool for in situ speciation measurements of trace metals under natural waters. Their attractive features include the ability to separate and preconcentrate target species in a single step. A PLM comprising didecyl 1,10 diaza crown ether - lauric acid in phenylhexane/toluene (1:1) transports Cu, Pb, Cd and Zn across a microporous membrane from aqueous phase of interest to a stripping solution containing a strong ligand. Preconcentration factors in the range 100 - 3000 can be obtained in 5 - 120 min and a strip solution containing a strong complexing ligand. Detection limits of less than 10 pmol. L can then be achieved in real time by voltammetry at a Hg-Ir microelectrode. A theoretical transport model has been developed to interpret metal speciation and validated for Cu complexed to a selection of synthetic and natural ligands. -1
102
© 2002 American Chemical Society Taillefert and Rozan; Environmental Electrochemistry ACS Symposium Series; American Chemical Society: Washington, DC, 2002.
103
Downloaded by NANYANG TECHNOLOGICAL UNIV on June 3, 2016 | http://pubs.acs.org Publication Date: February 14, 2002 | doi: 10.1021/bk-2002-0811.ch006
Introduction The importance of trace element speciation analysis in environmental samples is widely recognized. In natural water, trace metals exist under various chemical forms such as the free hydrated ions, inorganic and organic complexes and metals associated with colloidal particles (7-5). These play various roles in geochemical and biogeochemical cycling of elements, including transport, bioaccumulation, and toxicity. The determination offreemetal ion concentration is therefore important for understanding these processes. Trace metals in natural waters, are present at low total concentration (
