Quantitation of anabolic hormones and their metabolites in bovine serum and urine by liquid chromatography-tandem mass spectrometry

A specific and sensitive method based on tandem mass spectrometry with on-line high-performance liquid chromatography using atmospheric pressure chemical ionisation (LC–APCI-MS–MS) for the quantitation of anabolic hormone residues (17β-19-nortestosterone, 17β-testosterone and progesterone) and their major metabolites (17-19-nortestosterone and 17-testosterone) in bovine serum and urine is reported. [²H₂]17β-Testosterone was used as internal standard. The analytes were extracted from urine (following enzymatic hydrolysis) and serum samples by liquid–liquid extraction and purified by C₁₈ solid-phase extraction. Ionisation was performed in a heated nebulizer interface operating in the positive ion mode, where only the protonated molecule, [M+H]⁺, was generated for each analyte. This served as precursor ion for collision-induced dissociation and two diagnostic product ions for each analyte were identified for the unambiguous hormone confirmation by selected reaction monitoring LC–MS–MS. The overall inter-day precision (relative standard deviation) ranged from 6.37 to 2.10% and from 6.25 to 2.01%, for the bovine serum and urine samples, respectively, while the inter-day accuracy (relative error) ranged from −5.90 to −3.18% and from −6.40 to −2.97%, for the bovine serum and urine samples, respectively. The limit of quantitation of the method was 0.1 ng/ml for all the hormones in bovine serum and urine. On account of its high sensitivity and specificity the method has been successfully used to confirm illegal hormone administration for regulatory purposes.     

Single and double A3-coupling (aldehyde-amine-alkyne) reaction catalyzed by an air stable copper(I)-phosphole complex

An air stable copper(I)-phosphole complex, [CuCl{2,5-bis(2-thienyl)-1-phenylphosphole}₂] (1), was utilized as a catalyst in single and double A³-coupling reactions for preparing mono- and bi-propargylamines. A variety of aldehydes, amines and terminal alkynes were tested. Most of these reactions led to formation of the expected propargylamines in good yields using low amounts catalyst and obviating both the use of purified reagents as employ of a glovebox.     

Photo-induced pyridine substitution in cis-[Ru(bpy)(2)(py)(2)]Cl(2): a snapshot by time-resolved X-ray solution scattering

Determination of transient structures in light-induced processes is a challenging goal for time-resolved techniques. Such techniques are becoming successful in detecting ultrafast structural changes in molecules and do not require the presence of probe-like groups. Here, we demonstrate that TR-WAXS (Time-Resolved Wide Angle X-ray Scattering) can be successfully employed to study the photochemistry of cis-[Ru(bpy)(2)(py)(2)]Cl(2), a mononuclear ruthenium complex of interest in the field of photoactivatable anticancer agents. TR-WAXS is able to detect the release of a pyridine ligand and the coordination of a solvent molecule on a faster timescale than 800 ns of laser excitation. The direct measurement of the photodissociation of pyridine is a major advance in the field of time-resolved techniques allowing detection, for the first time, of the release of a multiatomic ligand formed by low Z atoms. These data demonstrate that TR-WAXS is a powerful technique for studying rapid ligand substitution processes involving photoactive metal complexes of biological interest.     

On the effect of gravity on the bifurcation of rectangular closed-loop thermosyphon

Closed-loop thermosyphons are systems in which heat is transferred from a source to a sink by means of a natural convective flow, i.e. without the help of mechanical pumping. In fact, the dynamics of such systems strongly depend both on the thermal boundary conditions and on the gravitational field in which they operate. While the effect of variations of the boundary conditions has been extensively analysed in the last decades, the dependence on gravity has never been explicitly studied.The aim of this paper is to examine the effect of variations of gravity as well as that of thermal boundary conditions on the dynamics of natural circulation loops. Such an analysis might point out some useful applications for the cooling of a generic source in reduced gravity conditions.To this purpose an experimental campaign was performed on a natural circulation operating under a gravity field varying in the range between 10^–2 g and 1.8 g, with g = 9.81 ms^–2. The dynamical behaviour detected during the experiment was used for the validation of a mathematical model, previously validated under terrestrial gravity conditions. Model simulations were found to satisfactorily reproduce the dynamics of the system under variable gravity. This proved the possibility to use the model for the construction of bifurcation diagrams describing the behaviours of natural circulation loops under variations of both the gravitational field and the thermal boundaries.     

Gas-phase observation of multiply charged C60 anions

Gas-phase observation of C60(1-), C60(3-), and C60(4-) anions generated at platinum and gold electrodes and detected by electrochemical/electrospray mass spectrometry is reported. The anions were electrochemically generated from solutions of C60 dissolved in toluene/acetonitrile as well as from reduction of C60 films on gold electrode surfaces. The gas-phase observation of C60(3-) and C60(4-), despite the fact that they have negative electron affinities, is a result of a Coulombic barrier to electron loss. The fact that C60(2-) was not detected in these experiments is ascribed to its limited solubility under the reaction conditions. These studies, which demonstrate the gas-phase kinetic stability of C60(3-) and C60(4-), illustrate the promise of electrochemical/electrospray mass spectrometry for the study of metastable anions.     

Generalized surface thermodynamics with application to nucleation

Gibbs formulated a complete and general thermodynamics for surfaces in multicomponent fluid systems. When considering solid–fluid surfaces, he restricted attention to single-component solids in contact with fluids that could contain multiple components. Attempts that have been offered to generalize Gibbs’ results for surfaces between multicomponent solids and fluid are problematic owing to the difficulty that the surface chemical potentials for components that also reside on substitutional lattice sites in the solids are not well defined. Therefore any expressions involving these surface chemical potentials, such as the conventional definition of the surface energy, will also not be well defined. In order to formulate a general thermodynamics of equilibrium that takes into account capillary effects in systems containing surfaces between a multicomponent solids and fluids, it is shown that the concept of thermodynamic availability (exergy) can be employed that, when applied to surfaces, depends on the extensive but not the intensive variables (such as the chemical potentials) of the surfaces. Using this approach, Gibbs–Thomson–Freundlich effects for finite-size solids, an adsorption equation for solid–fluid surfaces and the thermodynamics of nucleation during solidification can be treated in a straightforward manner without referring to the ill-defined surface chemical potentials. A derivation is given that appears to be the first one that properly generalizes Gibbs’ analysis for the reversible work to form a critical nucleus to the case of solidification.     

Polyallylammonium Ferrocyanide Films for Trace Water Detection in Halogenated Solvents

Polyallylammonium films with electrostatically bound ferrocyanide were formed by electrochemically reducing ferricyanide ions in the presence of polyallylammonium chloride. These films could be deposited onto the surfaces of Pt, Au or SnO₂ electrodes. In anhydrous organic electrolyte solutions, these films are electroinactive but become electroactive after the addition of trace water. For concentrations of water from 0.0 to 0.12% in chlorinated solvents, the electroactivity is linear with water concentration. The linearity between concentration of water and electroactivity can be exploited to develop a subsaturation trace water sensor.