A rapid and specific derivatization procedure to identify acyl‐glucuronides by mass spectrometry

A simple procedure is described to identify acyl‐glucuronides by coupled liquid chromatography/mass spectrometry after derivatization to a hydroxamic acid with hydroxylamine. The reaction specificity obviates the need for isolation of the acyl‐glucuronide from an extract. Glucuronides derived from carbamic acids, and alkyl‐ and aromatic amines, are inert to the derivatization reaction conditions, making the hydroxamic acid derivative a fingerprint for acyl‐glucuronides. Copyright © 2010 John Wiley & Sons, Ltd.     

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Über jodometrische Mikrobestimmung von JO3′ und Cr2O7″ in kleinen Konzentrationen Verwendung von Silberkatalyse

Analytical and Bioanalytical Chemistry -     

Zeno Product Formula Revisited

We introduce a new product formula which combines an orthogonal projection with a complex function of a non-negative operator. Under certain assumptions on the complex function the strong convergence of the product formula is shown. Under more restrictive assumptions even operator-norm convergence is verified. The mentioned formula can be used to describe Zeno dynamics in the situation when the usual non-decay measurement is replaced by a particular generalized observables in the sense of Davies.     

Direct Bioelectrocatalysis by NADP‐Reducing Hydrogenase from Pyrococcus furiosus

The direct bioelectrocatalysis by an NAD(P)‐reducing hydrogenase is reported for the first time. In contrast to previous attempts to involve similar enzymes in bioelectrocatalysis [1–4], which were in fact unsuccessful, in our report an effective electrocatalysis by Pyrococcus furiosus hydrogenase is convincingly shown by (i) achievement of the hydrogen equilibrium potential and (ii) a high current of hydrogen oxidation (0.3 mA cm^?2 at 100 mV overpotential and at 75 °C). The latter is just a few times lower compared to enzyme electrodes based on NAD(P)‐independent hydrogenases.     

Cyclodextrins as chiral stationary phases in capillary gas chromatography. Part IV: Heptakis(2,3,6-tri-O-pentyl)-β-cyclodextrin

O-Perpentylated β-cyclodextrin has been evaluated as chiral stationary phase in capillary gas chromatography. Enantioselectivity is observed towards many chiral hydroxy compounds, including cyanohydrins and carbohydrates. Most importantly, the enantiomers of many olefins and alkyl halides can be resolved on this chiral phase. The thermal stability of the cyclodextrin derivative exceeds 200°C.     

Two Hexagonal Series of Lanthanoid(III) Oxide Fluoride Selenides: M6O2F8Se3 (M = La – Nd) and M2OF2Se (M = Nd,Sm, Gd – Ho)

Two hexagonal series of lanthanoid(III) oxide fluoride selenides with similar structure types can be obtained by the reaction of the components MF₃, M₂O₃, M, and Se in sealed niobium tubes at 850 °C using CsI as fluxing agent. The compounds with the lighter and larger representatives (M = La – Nd) occur with the formula M₆O₂F₈Se₃, whereas with the heavier and smaller ones (M = Nd, Sm, Gd – Ho) their composition is M₂OF₂Se. For both systems single‐crystal determinations were used in all cases. The compounds crystallize in the hexagonal crystal system (space group: P6₃/m) with lattice parameters of a = 1394–1331 pm and c = 403–372 pm (Z = 2 for M₆O₂F₈Se₃ and Z = 6 for M₂OF₂Se). The (M1)³⁺ cations show different square antiprismatic coordination spheres with or without an extra capping fluoride anion. All (M2)³⁺ cations exhibit a ninefold coordination environment shaped as tricapped trigonal prism. In both structure types the Se^2– anions are sixfold coordinated as trigonal prisms of M³⁺ cations, being first condensed by edges to generate trimeric units and then via faces to form strands running along [001]. The light anions reside either in threefold triangular or in fourfold tetrahedral cationic coordination. For charge compensation, both structures have to contain a certain amount of oxide besides fluoride anions. Since F^– and O^2– can not be distinguished by X‐ray diffraction, bond‐valence calculations were used to address the problem of their adjunction to the available crystallographic sites.