Fractionation of Cu, Pb and Zn in certified reference soils SRM 2710 and SRM 2711 using the optimized BCR sequential extraction procedure

Sequential extraction of metals from solid media is a common analytical tool used in environmental and exploration geochemistry. A number of procedures exist, but without harmonization and standardization, meaningful comparisons are tenuous without baseline data. A newly developed, standardized sequential extraction procedure (optimized BCR) was applied to two contaminated certified reference soils from Montana, US (SRM 2710 and SRM 2711) for Cu, Pb and Zn. Four operationally defined fractions were isolated, acid extractable, reducible, oxidizable, and residual (by aqua regia). Fraction-specific concentrations, percentages and recoveries for Cu, Pb and Zn were used to explore differences between the optimized BCR procedure and three other sequential extraction schemes with published data for SRM 2710 and 2711 (i.e. Tessier scheme, Geological Survey of Canada scheme and the original BCR scheme). Results indicate significant differences between the four schemes, even for schemes that are closely associated (i.e. the original and optimized BCR schemes). Order-of-magnitude fraction-specific concentration differences were observed, especially for Pb in the reducible fraction. Differences between schemes are worrisome because trends varied between metals, between fractions and between reference soils. These data reinforce the need for increased adoption of standardized sequential extraction procedures and further examination of different solid media.     

A biological paleoindicator for early lake acidification: Mallomonadacean (Chrysophyceae) scale abundance in sediments

The Science of Nature -     

Phthalide als Hauptbestandteile des ätherischen Öls der Früchte vonMeum athamanticum Jacq.

The Science of Nature -     

Insektenpheromone

Pheromones — semiochemicals used by insects for intraspecific chemical communication — can be isolated and with special analytical techniques their chemical structure elucidated. With stereoselective synthesis methods, presented by the preparation of sex attractants and aggregating pheromones of moths and beetles, respectively, a synthetic access to compounds is given which can be used for behavior manipulation of insects. Aside the importance of these compounds for investigations of the sensoric process the possibility of their application in an integrated and biological pest control is discussed.     

Prenatal diagnosis of a true mosaic trisomy 20 substantiated by demonstration of a gene dosage effect for adenosine deaminase (ADA)

Fibroblasts from a fetus with the prenatal diagnosis of mosaic trisomy 20 were cloned by dilution plating. Adenosine deaminase (ADA), a biochemical marker for chromosome 20, was assayed in trisomic clones and normal clones as control. The cytogenetic diagnosis was substantiated by demonstration of a triplex gene dosage effect for ADA in the trisomic cells.