Characterization and application of isotope-substituted (13C15)-deoxynivalenol (DON) as an internal standard for the determination of DON

The powerful combination of liquid chromatography and mass spectrometry (MS) is often limited by matrix effects during ionization in the MS ion source. The use of fully isotope-substituted (¹³C₁₅)-deoxynivalenol ((¹³C₁₅)-DON) as an internal standard (IS) corrects matrix effects and improves the accuracy of analytical methods using mass spectrometry for the quantitative determination of the Fusarium mycotoxin deoxynivalenol (DON). The IS was characterized with respect to its chromatographic purity by liquid chromatography-ultraviolet light and its isotope distribution by time-of-flight mass spectrometry. Its low-energy collision-induced dissociation behaviour was compared with DON. Moreover, this work describes the successful application of (¹³C₁₅)-DON as IS for the determination of DON in maize using high-performance liquid chromatography (HPLC) electrospray (ESI) with tandem mass spectrometry. The results demonstrate that the IS can successfully correct for fluctuations during extraction and clean-up of the sample as well as the ionization of DON in the MS ion source. Random variations in ionization affect the IS in the same way as the analyte. Recoveries for DON in maize of 76% ± 1.9% (external calibration) or 101% ± 2.4% (internal calibration) were reached, respectively, after sample clean-up.     

Aspects of endowment: A query theory of value construction.

How do people judge the monetary value of objects? One clue is provided by the typical endowment study (D. Kahneman, J. L. Knetsch, & R. H. Thaler, 1991), in which participants are randomly given either a good, such as a coffee mug, that they may later sell ("sellers") or a choice between the good and amounts of cash ("choosers"). Sellers typically demand at least twice as much as choosers, inconsistent with economic theory. This result is usually explained by an increased weighting of losses, or loss aversion. The authors provide a memory-based account of endowment, suggesting that people construct values by posing a series of queries whose order differs for sellers and choosers. Because of output interference, these queries retrieve different aspects of the object and the medium of exchange, producing different valuations. The authors show that the content and structure of the recalled aspects differ for selling and choosing and that these aspects predict valuations. Merely altering the order in which queries are posed can eliminate the endowment effect, and changing the order of queries can produce endowment-like effects without ownership. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Preparation of cellulose filters with covalently bound dithiocarbamate, 8-hydroxyquinoline,and aminocarboxylic acid functional groups

Filter papers with covalently bound chelating groups are produced with the aim to enrich metal ions simultaneously for measurement by X-ray fluorescence spectrometry. The selectivity of the chelating groups to transition elements is of utmost importance. Some analytically important chelating groups dithiocarbamate-, 8-hydroxyquinoline-derivatives, and aminocarboxylic acid (EDTA analogue) are immobilized on cellulose filter papers. These filters are produced in a flow reactor, filled with commercially prefabricated analytical grade filter papers. They are synthesized in a three-step-reaction. First, an epoxyactivated cellulose is produced which in the second step is converted into an aminocellulose. This aminocellulose is the starting material for the dithiocarbamate-, the 8-hydroxyquinoline, and EDTA-analogue cellulose. The immobilization of 8-hydroxyquinoline or 8-hydroxyquinoline-5-sulfonic acid is accomplished through an aminomethylation. The analytically useful capacity of the various chelating filter papers is for dithiocarbamate, 8-hydroxyquinoline, 8-hydroxyquinoline-5-sulfonic acid, and EDTA-analogue derivatives 600, 700, 400, and 600 μmol/g, respectively.