Biomass sorbent for the extraction of platinum from environmental waters

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Researchers from the University of Bialystok at Poland have reported an extraction procedure which uses immobilized microorganisms as active sorbent for the isolation and preconcentration of platinum from water samples. The article, recently published in Microchimica Acta, describes the on-line combination of the extraction step with the final chemiluminescent determination of the target analyte using a flow injection manifold.

Biomass sorbents based on different microorganisms have been extensively used in inorganic chemical analysis since the cell walls present interaction sites towards metallic ions. These sites present different interaction mechanisms such as ionic exchange, physical adsorption, complexation or microprecipitation. The type of interaction directly depends on the chemical composition of the cell wall, which is characteristic of each microorganism. In this case, the authors proposed a filamentous fungus (Aspergillus sp) which presents a polysaccharide rich wall, being chitin the most abundant component. According to the final results, in this application ion exchange is the most probably mechanism of retention of Pt. In fact, Pt in the form [PtCl6]-2 is retained by its interaction with protonated sites of the cell wall.

The proposed methodology, as it has been previously described, consists of the coupling of the extraction with the final determination step which takes advantage of the catalytic activity of Pt in the chemical oxidation of luminol in alkaline media. The chemilumiscent reaction produces a light intensity which directly depends on the Pt presence allowing its determination at low concentration levels. The general procedure can be directly applied to natural waters since the effect of interfering ions is low enough. However, a previous cleaning with reversed phase sorbents is required when wastewaters are processed.

Readers are referred to the original article to further details about the proposal. The comparison of the biosorbent with those obtained with algae or yeast is especially interesting. The article is published under the open access modality.
 
References:
Link to the article: Sorption of platinum on immobilized microorganisms for its on-line preconcentration and chemiluminescent determination in water samples.
Link to the article: Microorganisms in inorganic chemical analysis.

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