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M Vidal

Publications and source records attributed to M Vidal.

206 records · Page 12Linked to original sources
PubMedDate not supplied

Prediction of trace element mobility in contaminated soils by sequential extraction.

The modified three-step sequential extraction procedure proposed by the Community Bureau of Reference (or Bureau Communautaire de Reference, BCR) was used to predict trace element mobility in soils affected by an accidental spill comprising arsenopyrite- and heavy metal-enriched sludge particles and acid waste waters. The procedure was used to obtain the distribution of both the major (Al, Ca, Fe, Mg, and Mn) and trace elements (As, Bi, Cd, Cu, Pb, Tl, and Zn) in 13 soils of contrasting properties with various levels of contamination and in the sludge itself. The distributions of the major elements enabled us to confirm the main soil fractions solubilized in each of the three steps, and, in turn, to detect the presence of pyritic sludge particles by the high Fe extractability obtained in the third step. Cadmium was identified as being the most mobile of the elements, having the highest extractability in the first step, followed by Zn and Cu, Lead, Tl, Bi, and As were shown to be poorly mobile or nonmobile. In the case of some of the trace elements, the residual fractions decreased at higher levels of contamination, which was attributed to the anthropogenic contributions to the polluted samples. Comparison with soil-plant transfer factors, calculated in plants growing in the affected area, indicated that a relative sequence of trace element mobility was well predicted from data of the first step.

Accidents↗
PubMedDate not supplied

Model systems for oxidative drug metabolism studies. Catalytic behavior of water-soluble metalloporphyrins depends on both the intrinsic robustness of the catalyst and the nature of substrates.

Sulfonated manganese and iron porphyrins have been used as catalysts in attempts to mimick the oxidation of acetaminophen and two ellipticine derivatives by horseradish peroxidase. Cofactors were potassium monopersulfate for the synthetic catalyst and hydrogen peroxide for the natural enzyme. Hindered metalloporphyrins, i.e. with ortho positions of the meso-phenyl rings substituted with methyl groups [iron(III) and manganese(III) derivatives of octasodium mesotetrakis(3,5-disulfonatomesityl)porphyrin], were shown to be at least 10 times more robust than unsubstituted derivatives [iron(III) and manganese(III) derivatives of tetrasodium meso-tetrakis(4-sulfonatophenyl)porphyrin] when activated in the absence of substrate. The catalytic activity depends on the nature of the substrate as shown by a decrease or an increase in reactivity observed, respectively, in the oxidation of acetaminophen or ellipticine derivatives catalyzed by hindered metalloporphyrins compared with nonhindered ones. Only sterically hindered metalloporphyrins, even in the case of lowered reactivity, were allowed to mimick the behavior of horseradish peroxidase when activated in the absence of substrate (stability toward autodegradation) and in the course of repeated infusion of substrate (retained catalytic activity as time advances).

Acetaminophen↗