High-sensitivity quantitation of cabergoline and pergolide using a triple-quadrupole mass spectrometer with enhanced mass-resolution capabilities

Quantitative analysis of pharmaceuticals with low systemic plasma levels requires the utmost in sensitivity and selectivity from the analytical method used. A recently introduced triple-quadrupole mass spectrometer with unique enhanced mass-resolution capability was evaluated in the analysis of two such drugs, cabergoline and pergolide, in plasma. Liquid chromatographic/electrospray ionization selected reaction monitoring determination of cabergoline in plasma at unit mass-resolution demonstrated improved sensitivity (50 fg on-column), coupled with suitable accuracy and precision over a broad linear dynamic range covering five orders of magnitude (50 fg to 5 ng on-column). Liquid chromatographic/atmospheric pressure chemical ionization selective reaction monitoring determination of pergolide in plasma also attained a high level of sensitivity (500 fg on-column) at unit mass-resolution, with accuracy and precision values well within pharmaceutical industry standards. Again, a linear dynamic range covering five orders of magnitude (500 fg to 50 ng on-column) was achieved for the assay. Utility of the enhanced mass-resolution feature of the triple-quadrupole mass spectrometer in the determination of pergolide resulted in an improvement in analyte sensitivity (250 fg on-column) and linear dynamic range (250 fg to 50 ng on-column).     

Characterization of coalitionally ordered games

Summary In the sequel we will derive sufficient and necessary conditions for the existence of certain numeric representations of simple games. In § 2 the above mentioned representation is given by a so called, coalitionally ordered function, i.e. a numeric function representing the desirability of each coalition in the class of all coalitions. Simple games which possess a c.o.f are called coalitionally ordered games. Sufficient and necessary criteria are given for a simple game to be a c.o.g. Analogously weighted majority games are characterized in § 3. The criteria to be presented are linked by properties of the desirability relation of a simple game. The concept of a desirability relation was introduced by Peleg 1978.

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Zusammenfassung Im folgenden werden wir hinreichende und notwendige Bedingungen zur Existenz von gewissen numerischen Darstellungen einfacher Spiele (simple games) herleiten. Diese oben genannte Darstellung wird in § 2 durch eine sogenannte coalitionally ordered function, gegeben, wobei wir darunter eine numerische Funktion verstehen, die die Desirability, jeder Koalition innerhalb der Klasse aller Koalitionen beschreibt. Einfache Spiele, die eine c.o.f besitzen, werden coalitionally ordered games genannt. Es werden hinreichende und notwendige Bedingungen dafür genannt, daß ein einfaches Spiel ein c.o.g ist. Analog werden gewichtete Abstimmungsspiele (weighted majority games) in § 3 charakterisiert. Die angegebenen Kriterien werden mit Eigenschaften der sogenannten desirability relation eines einfachen Spieles in Verbindung gebracht. Das Konzept einer desirability relation wurde von Peleg 1978 verwendet.

     

Substituent increments for the 1H-NMR. Chemical shifts of the 18- and 19-methyl protons of steroids. Part I: 9beta, 10alpha(retro)-steroids

This paper reports 261 substituent increments for the ¹H? NMR. chemical shifts (solvent: CDCl₃) of the 18- and 19-methyl protons of 9β, 10α(retro)-steroids relative to 5β,9β,10α,-androstane. The increments were calculated by a least-squares procedure from 1334 spectra of 759 different steroids.     

Sodium-iron fluorophosphate glasses: Part 2: EPR and mössbauer resonance study

EPR and Mössbauer measurements have been performed on sodium-iron fluorophosphate glasses. Mössbauer spectra show the presence of Fe³⁺ and Fe²⁺ both in octahedral coordination sites. However, for low iron concentration, EPR suggests a small number of Fe³⁺ tetrahedra coexisting with Fe³⁺ octahedra. On the basis of these results, Fe³⁺ tetrahedrally and/or octahedrally coordinated, connected with P(O, F)₄ tetrahedra would behave as a network-former cation, whereas Fe²⁺ would substitute for Na⁺ as a netweork-modifier. Long range magnetic order previously observed by magnetic measurements has been confirmed for iron-rich compositions.     

A memory‐efficient finite volume method for advection‐diffusion‐reaction systems with nonsmooth sources

We present a parallel matrix‐free implicit finite volume scheme for the solution of unsteady three‐dimensional advection‐diffusion‐reaction equations with smooth and Dirac‐Delta source terms. The scheme is formally second order in space and a Newton–Krylov method is employed for the appearing nonlinear systems in the implicit time integration. The matrix‐vector product required is hardcoded without any approximations, obtaining a matrix‐free method that needs little storage and is well‐suited for parallel implementation. We describe the matrix‐free implementation of the method in detail and give numerical evidence of its second‐order convergence in the presence of smooth source terms. For nonsmooth source terms, the convergence order drops to one half. Furthermore, we demonstrate the method's applicability for the long‐time simulation of calcium flow in heart cells and show its parallel scaling. © 2014 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq31: 143–167, 2015     

Diffraction problems with impedance conditions

The two- or three-dimensional electromagnetic diffraction problem for a half-plane impedance or reactance sheet belongs to a class of elliptic transmission problems of mixed type. Sobolev spaces of order 1 and ±1/2 are naturally involved according to the energy norm and the trace theorem, respectively. This operator theoretic approach presents the equivalence to systems of Wiener-Hopf equations and their solution in the sense of a well-posed problem with respect to the spaces under consideration. Slightly different impedance numbers for the two banks of the screen lead to a perturbation problem. All results yield direct a priori estimates for the solutions.