KINETIC STUDY OF LANTHANIDE INTERACTIONS WITH HUMIC SUBSTANCES BY TIME RESOLVED LASER INDUCED FLUORESCENCE
Kinetic methods of speciation provide an approximation to the kinetic behaviour of metal species in natural waters - generally, in dynamic rather than in equilibrium conditions. The objective of this paper is to investigate the kinetics of lanthanide complexation with natural organic ligands, using a stopped-flow apparatus coupled with equipment for Time Resolved Laser Induced Fluorescence. The excitation is provided by an excimer laser operated by XeCl mixtures. The short-lived background luminscence of humic compounds is eliminated by time-gating. The fluorescence emission of lanthanide species due to resonant energy transfer from the organic part of the complex is then measured. The results of kinetic runs at different pH and ionic strengths are reported for humic and fulvic acids of various origin. The measured rates of complex formation are lower for humic acids. The addition of competitive cations has a marked effect both on the time dependence and the amplitude of the fluorescence signal.
Bibliographic Reference: AVAILABLE FROM COMMISSION OF THE EUROPEAN COMMUNITIES, DG XIII-C-3, L-2920 LUXEMBOURG AS PAPER EN 34916 ORA
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Record Number: 1989128083100 / Last updated on: 1991-05-15
Original language: EN
Available languages: en