Piatina, T. California Institute of Technology, piatina@cco.caltech.edu
Hering, J. California Institute of Technology, jhering@cco.caltech.edu

 
DIRECT QUANTIFICATION OF METAL-ORGANIC INTERACTIONS BY SIZE-EXCLUSION CHROMATOGRAPHY AND INDUCTIVELY COUPLED PLASMA MASS-SPECTROMETRY
 
Metal-organic interactions significantly influence the geochemical cycling of trace metals and can control metal bioavailability and toxicity. Advanced analytical techniques have been applied to address some difficulties encountered in identifying and quantifying metal-organic species. In this method, size-exclusion chromatography is used for fractionation of dissolved organic compounds. Molecular size calibration of the column was performed with polystyrene-sulphonate standards and the effects of hydrophobic interactions on the column were determined. Model studies using copper and well-defined organic ligands demonstrated that the technique is subject to kinetic limitations, since labile metal-organic complexes can dissociate during fractionation on the column. Studies with strong organic ligands that form 1:1 complexes with metals have shown that such ligands are inert on the time scale of the column fractionation and that the distribution of Cu-ligand species determined analytically corresponds to the calculated equilibrium speciation. Metal concentrations in the column eluent (i.e., corresponding to each organic fraction) were determined by inductively coupled plasma mass-spectrometry without any further preparation. Application to dissolved organic matter (DOM) will include direct metal analysis of size-fractionated organics as well as metal-titration and ligand competition studies.
 
Day: Monday, Feb. 1
Time: 03:30 - 03:45pm
Location: Eldorado Hotel
 
Code: SS34MO0330E