Determination of Zn, B, Fe, Mg, Ca, Na and Si in anisette samples by inductively coupled plasma atomic emission spectrometry

A comparative study of several digestion methods of anisette samples has been carried out. Two dry ashing (DA) treatments as well as four wet ashing (WA) procedures using different mixtures of acids were applied for the sample mineralisation before analysis. Once the anisette samples were mineralised, the contents of Zn, B, Fe, Mg, Ca, Na and Si were determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES). Each method has been studied statistically and also attending to their feasibility. After performing the optimisation of the different treatments tested, it was concluded that one wet ashing method employing a HNO₃:H₂O₂ (10:1) mixture was the most suitable. This method was applied to the analysis of anisette samples. Na, Ca, Mg and Si were present in concentrations up to 215 mg l⁻¹ for Na, 11.6 for Mg, 6.2 for Ca and 5.1 for Si. Fe and B concentrations were not higher than 0.12 mg l⁻¹ and lower for Zn.     

Toxicity assessment of tamoxifen by means of a bacterial model

A strain of Bacillus stearothermophilus was used as a model to study physical perturbations induced in the membrane by the cytostatic tamoxifen (TAM). This study was carried out using two lines of criteria: (1) bacterial growth, and temperature growth range, with determination of growth parameters as a function of TAM concentration; and (2) biophysical studies by differential scanning calorimetry (DSC) and by means of two fluorescent probes to evaluate perturbations promoted by the drug on the structural order of bacterial lipid membranes. The inhibition of growth induced by TAM, the structural bilayer disordering, and the shift in the phase transition temperature to a lower range were also determined in the presence of Ca²⁺, i.e., a natural membrane stabilizer, to elucidate further perturbing effects of TAM on membranes with putative implications in cell toxicity. Growth inhibition promoted by TAM is potentiated by an increase in growth temperature above the optimal range, but attenuated or relieved by the addition of 2.5 mM Ca²⁺ to the culture medium. Consistently, fluorescence polarization and DSC studies showed that Ca²⁺ ions (2.5 mM) effectively compensated for the destabilizing effects promoted by TAM in bacterial lipid membranes.     

LC Determination of Anethole in Aniseed Drinks

A method for the determination of anethole in aniseed drinks by high performance liquid chromatography (HPLC) is proposed. A C-18 column and a methanol-water (80:20, v/v) mobile phase with isocratic elution were used. UV detection at 257 nm was carried out. Validation was performed according to the EURACHEM guidelines, considering precision, trueness, robustness, linearity and sensitivity. The detection and quantification limits were 2.3 and 7.7 μg L⁻¹, respectively. Recoveries of 95–101% were obtained. Repeatability, calculated as relative standard deviation was 0.9%. Reproducibility under intermediate precision conditions, expressed as relative standard deviation, was 1.6%. The method was compared with the gas chromatographic one, proposed by the European regulations.     

Non-Selective Toxicological Effects of the Insect Juvenile Hormone Analogue Methoprene. A Membrane Biophysical Approach

The Gram-positive bacterium, Bacillus stearothermophilus, was used as a model organism to identify the non-selective toxic effects of the currently used insecticide methoprene (isopropyl(2E,4E)-11-methoxy-3,7,11-trimethyl-2,4-dodecadienoate). A significant decrease of the yield of bacterial cultures and a premature appearance of ultrastructural abnormalities in cells cultured in the presence of the insecticide were taken as indicators of cytotoxicity. A putative correlation of this cytotoxicity with methoprene-induced perturbations on membrane lipid organization was investigated, using differential scanning calorimetry and the fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH) and its propionic acid derivative (DPH-PA). The membrane physical effects depended on the lipid bilayer composition and packing. The most striking effect was a progressive broadening and shifting to lower temperatures, with increasing methoprene concentrations, of the main transition phase of the dimyristoyl- or dipalmitoylphosphatidylcholine bilayers and of the lateral phase separation of liposomes reconstituted with the lipid extracts of B. stearothermophilus.     

含铁磁耦合Ni3单元的均苯三甲酸桥联双层镍(II)配合物

使用均苯三甲酸与碳酸镍在水热条件下反应得到了一例新的二维双层Ni(II)配位聚合物Ni3(BTC)2(μ-H2O)26H2O。二维层包含syn-syn羧酸桥和水桥连接的三核Ni3单元,进一步用均苯三甲酸上的苯环连接成二维层状结构。磁性研究表明,相邻Ni2+离子间存在弱的铁磁耦合作用。水桥连镍离子的桥联键角为122.8(3)deg,所以通过该水桥镍离子间应该呈现反铁磁耦合。因此,实验结果证明了syn-syn羧酸桥传递铁磁耦合,而且铁磁耦合大于反铁磁作用,最终配合物呈弱的铁磁耦合。基于本工作和文献报道的含syn-syn 羧酸混合桥联镍配合物的磁性,我们总结出下面结论：Ni–O–C–O–Ni的共面性与否决定了配合物的磁性。共面性好的Ni–O–C–O–Ni导致中等强度的反铁磁耦合,而共面性差会消弱反铁磁作用,甚至出现由反铁磁变为铁磁耦合。标题配合物中羧酸桥所传递的铁磁性可能就归因于Ni–O–C–O–Ni的不共平面性。因此,与含羧酸桥的混合桥联双核铜(II)配合物类似,轨道补偿效应(the orbital complementary effect (OCE))对于解释水/羧酸混合桥联镍(II)配合物的磁性也同样适用。     

Supercritical carbon dioxide extraction of Usnea longissima (L.) Ach.: Optimization by Box-Behnken design (BBD)

Usnic acid (UA) was extracted from Usnea longissima (L.) Ach. in supercritical carbon dioxide (SC-CO₂) medium. The selected process parameters were extraction temperature (35–45 °C), amount of co-solvent (0%–5%) and extraction time (5–9 h). These parameters were applied to Box-Behnken design (BBD) belonging to response surface methodology (RSM) to determine optimum process parameters for the highest amount of UA in the extract. g UA/100g lichen, extraction yield % and UA content values were calculated in the range of 0.045–0.317, 2.77–5.4 and 71%–82% in different experimental conditions, respectively. The optimum conditions were predicted as 42 °C, 4.3% (ethanol) and 7.48 h. It was determined that the predicted and experimental values of g UA/100g lichen were compatible, and the suggested model was valid.