Simultaneous determination of ten amphetamine designer drugs in human whole blood by capillary electrophoresis with diode array detection

In recent years, a number of new designer drugs have entered the illicit drug market. The methylenedioxyderivatives of amphetamine represent the largest group of designer drugs. This paper describes a method for screening for and simultaneously quantifying 10 2,5-methylenedioxy-derivatives of amphetamine and phenethylamine in human whole blood, using capillary electrophoresis (CE) with diode array detection (DAD). Using an aqueous pH 2.5 phosphate buffer, CE analysis gave peaks with good symmetry and reproducible migration times. Under these experimental conditions, the 10 amphetamines were resolved in 15 min and without interference from biological matrices (blood). Their identification by migration time was confirmed by their UV spectra recorded with a DAD (190-350 nm). The main advantages of the present method lie in its simplicity, clean and reliable extraction from human whole blood and simultaneous detection and quantification by CE-DAD. The applicability of the method was demonstrated by analysis of in vivo rat blood samples. The method was validated according to international guidelines.     

Low-energy electron scattering by cubane: resonant states and Ramsauer-Townsend features from quantum calculations in the gas phase

Calculations are carried out, using a nonempirical modeling of the interaction potential and solving the quantum scattering coupled channel equations, for low energy electron scattering from cubane (C8H8) molecules in the gas phase. Total integral cross sections are obtained and partial contributions are analyzed for the most important irreducible representations that describe the continuum electron in the Oh molecular symmetry. Several trapping resonances are found and analyzed in terms of the molecular-type features of the resonant electron states associated with them. A Ramsauer-Townsend minimum is also found and its possible behavior related to features of the scattering length as k --> 0.     

Experimental evidence for a variable first coordination shell of the cadmium(II) ion in aqueous, dimethyl sulfoxide, and N,N'-dimethylpropyleneurea solution

A combined extended X-ray absorption fine structure (EXAFS) and large angle X-ray scattering (LAXS) investigation has been performed to evaluate the coordination structure of the cadmium(II) ion in aqueous, dimethyl sulfoxide, and N,N'-dimethylpropyleneurea (dmpu) solutions. This approach has singled out the existence of a flexible coordination shell around the cadmium(II) ion in aqueous and dimethyl sulfoxide solutions, whereas a regular octahedral complex is detected in dmpu. The EXAFS and LAXS techniques provide different values of the Cd-O first shell distance (2.27(1) A and 2.302(5) A, respectively) for the hydrated and dimethyl sulfoxide solvated complexes, and this discrepancy is originated by the simultaneous presence of hexa- and heptacoordinated complexes in solution, giving rise to a broad distribution of distances around the ion. These findings demonstrate that, in solution, the cadmium(II) ion forms quite flexible hydration and dimethyl sulfoxide solvate complexes undergoing a solvent exchange with unusually stable seven-coordinated intermediate complexes, and therefore the mean ion-solvent distance is longer in solution than in the solid state. In the dmpu solution, due to the bulkiness of the solvent molecules, the octahedral cadmium(II) solvate is extremely crowded and it is not possible for a seventh ligand to enter the inner-coordination shell. This investigation shows that the combined analysis of the EXAFS and LAXS data allows a reliable determination of the structural properties of electrolyte solutions, also in the presence of flexible coordination shell with a variable number of coordinating molecules.     

Reactions of benzotriazoles with diethyl ethoxymethylenemalonate; ethylation and michael addition. Comparison with other esters and N-heterocycles

Benzotriazole and its 5-methyl-and 5-nitro derivatives react with diethyl ethoxymethylenemalonate by ethylation at each of the ring N-atoms and through Michael addition, to give the isomeric esters ethyl (E/Z) 3-[5(6)-R-benzotriazol-1-yl]propenoates. Benzotriazole and its 5-nitro derivative react similarly with ethyl acetoacetate but N-ethyl derivatives are obtained in lower yields. Other 1,2,3-triazoles derivatives and indole were ineffective in this reaction while benzimidazole produced similar results but accompanied with a small amount of a benzimidazoline addition product, whose structure has been determined by crystallo-graphic analysis.     

Effect of gramicidin on phospholipid-modified monolayers and on ion transfer at a liquid-liquid interface.

The interaction of hybrid lipid/gramicidin A (gA) monolayers with dextran sulfate (DS) and the effect of this interaction on ion transfer at a liquid-liquid interface is reported. The interfacial and physicochemical properties are studied with Langmuir-Blodgett (LB) and electrochemical techniques. The results obtained from compression isotherms demonstrate that the interactions between the different species in the hybrid monolayer vary according to the chemical nature of the lipid (hydrocarbon region and charge of the head group). Interfacial capacitance measured with AC voltammetry indicates that the DS chains form a rather flat and compact layer when adsorbed to either zwitterionic or negatively charged phospholipid monolayers, and that calcium, even at low concentrations, interacts with the monolayers. These results are successfully described by a model based on the solution of the Poisson-Boltzmann equation in the interfacial region. Ion transfer and interactions with the lipid/gA/DS-modified monolayers were also studied with electrochemical techniques. Admittance data show that although the studied ions are not using gA channels for the transfer through the lipid membranes, the incorporation of gA in the lipid domain and the adsorption of DS at the interface have a significant effect on ion transfer across the monolayers. This effect can be explained as a consequence of the modified surface charge and of the compactness of the lipid domain due to its interaction with gA and to calcium and DS adsorption at the interface. The ion-transfer rate, therefore, depends on the composition of the monolayer and the chemical nature of the ion.     

Essential oil composition and biological activity from Artemisia caerulescens subsp. densiflora (Viv.) Gamisans ex Kerguélen & Lambinon (Asteraceae), an endemic species in the habitat of La Maddalena Archipelago

The purpose of this study was to investigate the composition of the essential oil obtained from a population of Artemisia caerulescens subsp. densiflora growing in Razzoli, an island in the La Maddalena Archipelago (Sardinia, Italy). A. caerulescens sups. densiflora Viv. (Asteraceae), a wild herb, seldom studied in the Mediterranean, represents one of the many rare endemic species growing in North Sardinia. The essential oil composition was analysed by means of GC/MS analysis, which showed davana ethers as the major volatile components, accounting together for 17.5%, followed by (E)-nerolidol (4.5%), β-oplopenone (3.3%), cis-sabinene hydrate (5.2%) and terpinen-4-ol (4.7%). The oil was tested for antioxidant activity by means of DPPH test, inhibition of lipid oxidation test and hypochlorous acid test, which showed a quite interesting scavenger capacity. For the first time, we reported the cytotoxic activity of the essential oil of A. caerulescens subsp. densiflora, against three human tumour cell lines (A375, MDA-MB231 and HCT116), with IC₅₀ values in the range 5.20–7.61 μg/mL, which deserved further studies to support its use as chemopreventive agent. Finally, the antimicrobial activity of the essential oil, displayed on a panel of human pathogens, was very low.     

Potentiometric, spectroscopic, electrochemical and DFT characterization of oxovanadium(IV) complexes formed by citrate and tartrates in aqueous solution at high ligand to metal molar ratios: the effects of the trigonal bipyramidal distortion in bis-chelated species and biological implications

The complexation of VO(iv) ion with citrate (L(3-)), d-, l- and dl-tartrate (L(2-)) at high ligand to metal molar ratios was studied in aqueous solution through the combined application of potentiometric, spectroscopic (UV-vis and EPR) and electrochemical (cyclic voltammetry) techniques. Unlike in equimolar solution, mononuclear and not dinuclear species are formed with the binding of carboxylate-COO(-) and alcoholate-O(-) donors yielding mono- and bis-chelated species with VOLH, VOL, VOLH(-1) and VOL(2)H(-2) composition; for tartrates also the "sugar-like" (O(-), O(-)) coordination is involved in the vanadium binding at basic pH values giving rise to the formation of VOL(2)H(-3) and VOL(2)H(-4) complexes. Among the species formed, VOL(2)H(-2) is characterised by a strong distortion towards the trigonal bipyramid with the two V-O(alcoholate) bonds in the equatorial and the two V-O(carboxylate) bonds in the axial positions. The geometry and electronic absorption spectra of such complexes were simulated by DFT methods and it was found that in aqueous solution the distortion follows the steric hindrance of the substituents on the alpha-carbon atom and the hydrophobicity of the ligands. The results were compared with those displayed by simple alpha-hydroxycarboxylates (glycolate, 2-hydroxyisobutyrate, 2-ethyl-2-hydroxybutyrate and benzilate). The trigonal bipyramidal distortion was correlated with the values of: i) Deltalambda = lambda(2) - lambda(3), where lambda(2) and lambda(3) are the central bands in the electronic absorption spectrum; ii) |A(x) - A(y)|, where A(x) and A(y) are the (51)V hyperfine coupling constants along the x and y axes in the anisotropic EPR spectrum; iii) the half-wave potential E(1/2) of oxidation of VO(iv) to the corresponding VO(2)(v) species in the cyclic voltammogram. Finally, a discussion on the possible form of VO(iv)-citrate complexes in blood serum is presented, where it is found that the most relevant species under physiological conditions should be [VO(citrH(-1))](2-).     

Structural and dynamical properties of the Hg2+ aqua ion: a molecular dynamics study

Molecular dynamics simulations of the Hg2+ ion in aqueous solution have been carried out using an effective two-body potential derived from quantum mechanical calculations. A stable heptacoordinated structure of the Hg2+ first hydration shell has been observed and confirmed by extended X-ray absorption fine structure (EXAFS) experimental data. The structural properties of the Hg2+ hydration shells have been investigated using radial and angular distribution functions, while the dynamical behavior has been discussed in terms of reorientational correlation functions, mean residence times of water molecules in the first and second hydration shells, and self-diffusion coefficients. The effect of water-water interactions on the Hg2+ hydration properties has been evaluated using the SPC/E and TIP5P water models.     

Alpha-decay characteristics of neutron-deficient 190Po, 189Bi and 186Pb isotopes

The neutron-deficient ¹⁹⁰Po and ¹⁸⁹Bi isotopes have been produced in the 2n respectively p2n channels of the ⁴⁸Ti +¹⁴⁴ Sm reaction. Cross sections for different reaction channels are given. For ¹⁹⁰Po, improved values of α-energy E_α = 7550(15) keV and half-life T_1/2 = 1.9 _?0.4 ^+0.6 ms were measured. By using correlated α-decay chains an α-branching ratio of 0.50(25) was deduced for ¹⁸⁶Pb. The reduced α-width systematic is extended for both of these isotopes, confirming a persistence of the saturation towards the lighter Po isotopes and the absence of any anomalies for the neutron-deficient Pb isotopes. For ¹⁸⁹Bi improved values of E_α = 7300(15) keV and T_1/2 = 4.8(5) ms were measured.