Headspace Sorptive Extraction (HSSE) in the Headspace Analysis of Aromatic and Medicinal Plants

A new sampling technique, Headspace Sorptive Extraction (HSSE), is here applied for the first time to the headspace sampling of medicinal and aromatic plants. The analyte partition coefficient between HSSE‐PDMS stir bar and sample headspace (K₁), the concentration factor (CF), the reproducibility, and the minimum recoverable amount were determined by analyzing standard solution of high volatility C₅–C₇ compounds with different polarities and structures (cyclohexane, propyl acetate, hexanal, 1‐hexen‐3‐ol, isoamyl acetate, and 2‐heptanol). Four aromatic and medicinal plants, viz. rosemary (Rosmarinus officinalis L.), sage (Salvia officinalis L.), thyme (Thymus vulgaris L.), and valerian (Valeriana officinalis L.) were analyzed by HSSE‐GC with PDMS stir bars, and their concentration capacity was compared with those of S‐HS and HS‐SPME with different fibers. HSSE showed very high concentration capability with both standard and real sample components.     

Selenium: An Element of Life Essential for Thyroid Function

Selenium (Se), a microelement essential for life, is critical for homeostasis of several critical functions, such as those related to immune–endocrine function and signaling transduction pathways. In particular, Se is critical for the function of the thyroid, and it is particularly abundant in this gland. Unfortunately, Se deficiency is a very common condition worldwide. Supplementation is possible, but as Se has a narrow safety level, toxic levels are close to those normally required for a correct need. Thus, whether the obtaining of optimal selenium concentration is desirable, the risk of dangerous concentrations must be equally excluded. This review addressed the contribution by environment and food intake on Se circulating levels (e.g., geographical factors, such as soil concentration and climate, and different quantities in food, such as nuts, cereals, eggs, meat and fish) and effects related to its deficiency or excess, together with the role of selenium and selenoproteins in the thyroid pathophysiology (e.g., Hashimoto’s thyroiditis and Graves’ disease).     

The development of conductive composite surfaces by a diffusion-limited in situ polymerization of pyrrole in sulfonated polystyrene ionomers

Electrically conductive composite surfaces were prepared by a diffusion-controlled in situ polymerization of pyrrole in the surface layer of sulfonated polystyrene ionomer films. Premolded films of the ionomer sulfonic acid derivatives were sequentially immersed in aqueous solutions of pyrrole and FeCl₃, and polymerization occurred only where both the monomer and the oxidant were present. The penetration of the polypyrrole (PPy) into the film was controlled by varying the immersion time in the monomer solution. The amount of PPy produced depended on the immersion time of the film in the monomer and the degree of sulfonation of the ionomer. Surface conductivities of 10⁻⁴-10⁻¹ S/cm were achieved with PPy concentrations from 2 to 22 wt % and composite layers as thin as 15 μm. Intermolecular interactions occurred between PPy and the ionomer by proton transfer. Incorporation of PPy also increased the tensile strength of the ionomer film, significantly increased its modulus above T_g, and inhibited melt flow. © 1997 John Wiley & Sons, Inc.     

Flavonoids: Antiplatelet Effect as Inhibitors of COX-1

Flavonoids are compounds with a benzopyranic structure that exhibits multiple pharmacological activities. They are known for their venotonic activity, but their mechanism of action remains unclear. It is thought that, as this mechanism is mediated by prostaglandins, these compounds may interfere with the arachidonic acid (AA) cascade. These assays are designed to measure the antiplatelet aggregation capacity of quercetin, rutin, diosmetin, diosmin, and hidrosmin, as well as to evaluate a potential structure−activity ratio. In this paper, several studies on platelet aggregation at different concentrations (from 0.33 mM to 1.5 mM) of different flavone compounds are conducted, measuring platelet aggregation by impedance aggregometry, and the cyclooxygenase (COX) activity by metabolites generated, including the activity of the pure recombinant enzyme in the presence of these polyphenols. The results obtained showed that quercetin and diosmetin aglycones have a greater antiplatelet effect and inhibit the COX enzyme activity to a greater extent than their heterosides; however, the fact that greater inhibition of the pure recombinant enzyme was achieved by heterosides suggests that these compounds may have difficulty in crossing biological membranes. In any case, in view of the results obtained, it can be concluded that flavonoids could be useful as coadjuvants in the treatment of cardiovascular pathologies.     

HPLC—UV determination of pesticide residues at 0.01 ppm in apple and pear pulp used for baby food

Two distinct methods are described for determination of residues of ethiofencarb and triforine, and of diflubenzuron, teflubenzuron, and triflumuron at the 0.01 ppm level in apple and pear pulp used for baby food;recoveries are above 50%. Diflubenzuron, teflubenzuron, and triflumuron are extracted with a 1:1 mixture of dichloromethane and acetone, and the extracts are cleaned by SPE using C₁₈ as stationary phase and methanol as mobile phase. Ethiofencarb and triforine are extracted with dichloromethane, and the extracts cleaned using the same stationary phase but a 1:1 mixture of acetonitrile and water as mobile phase. Analysis of both groups of pesticides is by isocratic HPLC—UV at 210 nm using an RP-18 column and acetonitrile-water as mobile phase.     

Copper Complexes with New Pyridylpyrazole Based Ligands

We report the synthesis, characterization, and crystal structures of new ligands of the pyridinylpyrazole type, i.e., 3,5‐bis(4‐butoxyphenyl)‐1‐(pyridin‐2‐yl)‐1H‐pyrazole ( L ¹ ) and 3,5‐bis(4‐phenoxyphenyl)‐1‐(pyridin‐2‐yl)‐1H‐pyrazole ( L ² ) (Scheme 1), and the study of their coordination behavior towards Cu^I and Cu^II. The versatility of this type of ligand, which can give access to different coordination spheres about the metal center, depending on the nature of the copper starting material used in the preparation of the complexes (Scheme 2), is illustrated. Thus, pseudo‐tetrahedral Cu^I as well as six‐coordinated tetragonal and distorted tetragonal pyramidal Cu^II derivatives were obtained for [Cu(L)₂]PF₆, [Cu(Cl)₂(L)₂] (L= L ¹ , L ² ), and [Cu(Cl)( L ¹ )₂]PF₆, respectively. We also present a crystallographic support of a distorted octahedral cis‐bis(tetrafluoroborato‐κF)copper(II) compound found for [Cu(BF₄)₂( L ¹ )₂] ( 3 ).     

Initializing the Amplitude Distribution of a Quantum State

To date, quantum computational algorithms have operated on a superposition of all basis states of a quantum system. Typically, this is because it is assumed that some function f is known and implementable as a unitary evolution. However, what if only some points of the function f are known? It then becomes important to be able to encode only the knowledge that we have about f. This paper presents an algorithm that requires a polynomial number of elementary operations for initializing a quantum system to represent only the m known points of a function f.     

Asymmetrical flow field-flow fractionation with multi-angle light scattering detection for the analysis of structured nanoparticles

Synthesis and applications of new functional nanoparticles are topics of increasing interest in many fields of nanotechnology. Chemical modifications of inorganic nanoparticles are often necessary to improve their features as spectroscopic tracers or chemical sensors, and to increase water solubility and biocompatibility for applications in nano-biotechnology. Analysis and characterization of structured nanoparticles are then key steps for their synthesis optimization and final quality control. Many properties of structured nanoparticles are size-dependent. Particle size distribution analysis then provides fundamental analytical information. Asymmetrical flow field-flow fractionation (AF4) with multi-angle light scattering (MALS) detection is able to size-separate and to characterize nanosized analytes in dispersion. In this work we focus on the central role of AF4-MALS to analyze and characterize different types of structured nanoparticles that are finding increasing applications in nano-biotechnology and nanomedicine: polymer-coated gold nanoparticles, fluorescent silica nanoparticles, and quantum dots. AF4 not only size-fractionated these nanoparticles and measured their hydrodynamic radius (r_h) distribution but it also separated them from the unbound, relatively low-M_r components of the nanoparticle structures which were still present in the sample solution. On-line MALS detection on real-time gave the gyration radius (r_g) distribution of the fractionated nanoparticles. Additional information on nanoparticle morphology was then obtained from the r_h/r_g index. Stability of the nanoparticle dispersions was finally investigated. Aggregation of the fluorescent silica nanoparticles was found to depend on the concentration at which they were dispersed. Partial release of the polymeric coating from water-soluble QDs was found when shear stress was induced by increasing flowrates during fractionation.     

Visible and near-infrared absorption spectroscopy by an integrating sphere and optical fibers for quantifying and discriminating the adulteration of extra virgin olive oil from Tuscany

Because of its high price, extra virgin olive oil is frequently targeted for adulteration with lower quality oils. This paper presents an innovative optical technique capable of quantifying and discriminating the adulteration of extra virgin olive oil caused by lower-grade olive oils. An original set-up for diffuse-light absorption spectroscopy in the wide 400–1,700 nm spectral range was experimented. It made use of an integrating sphere containing the oil sample and of optical fibers for illumination and detection; it provided intrinsically scattering-free absorption spectroscopy measurements. This set-up was used to collect spectroscopic fingerprints of authentic extra virgin olive oils from the Italian Tuscany region, adulterated by different concentrations of olive-pomace oil, refined olive oil, deodorized olive oil, and refined olive-pomace oil. Then, a straightforward multivariate processing of spectroscopic data based on principal component analysis and linear discriminant analysis was applied which was successfully capable of predicting the fraction of adulterant in the mixture, and of discriminating its type. The results achieved by means of optical spectroscopy were compared with the analysis of fatty acids, which was carried out by standard gas chromatography.