Microsc. Microanal. Microstruct. 6, 41-51 (1995)
DOI: 10.1051/mmm:1995106

EELS-ESI Identification of Heterogeneous Suspensions of Aquatic Microparticles

Didier Perret, Charles-Philippe Lienemann et Denis Mavrocordatos

Institut de Chimie Minérale et Analytique, Université de Lausanne, BCH, CH-1015 Lausanne, Switzerland

Abstract
Submicron mineral particles in freshwaters represent an important proportion of the total particle number. These microparticles are frequently associated to macromolecular organic matter and have a high specific surface area; they might thus be strong heavy metal and nutrient scavengers in aquatic systems. Their non-artefacted characterization at the level of individual particles represents a promising challenge, while preservation of the undisturbed state of natural fragile specimens is a prerequisite. We have used a TEM-EELS-ESI procedure which allows the identification of mineral microparticles in individual model suspensions of iron oxides, aluminum oxides and clays in the presence of polysaccharides, at concentrations typical of natural levels. As expected, core-loss ionization edge intensities measured by this method are limited by the thickness of particles. Heterogeneous mixtures of the former microparticles/macromolecules were prepared in order to mimic natural specimens. Under optimum analytical conditions, it was possible to extract the very nature of these entities, to reveal low electron-density polysaccharides and even to identify microparticles masked within complex aggregates.

PACS
8270K - Emulsions and suspensions.
8280P - Electron spectroscopy (x-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.).
0781 - Electron and ion spectrometers.

Key words
Water pollution -- Suspended particle -- Microparticles -- Heterogeneous mixture -- Inorganic compound -- Qualitative analysis -- Electron spectrometry -- Imagery -- TEM -- Water treatment -- Water pollution -- Pollution -- Nuisances -- Applied sciences


© EDP Sciences 1995