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41.
Peter Q. Tranchida Simona Salivo Flavio A. Franchina Ivana Bonaccorsi Paola Dugo Luigi Mondello 《Analytical and bioanalytical chemistry》2013,405(13):4655-4663
The present investigation is focused on the development of a comprehensive two-dimensional GC (GC?×?GC) method, with dual MS/FID detection, for the qualitative and quantitative analysis of the entire unsaponifiable fraction of vegetable oils. The unsaponifiable fraction forms a minor, highly specific part of a vegetable oil, and can be used as an indicator of genuineness. The column set used consisted of a low-polarity first dimension, and a medium-polarity secondary one, both characterized by a high thermal stability. The use of dual detection enabled the attainment of both mass spectral information and relative % FID data. The complexity of the fingerprint, generated by the unsaponifiable fraction, fully justified the employment of the two-dimensional GC technology. Furthermore, two other GC?×?GC benefits contributed greatly to the attainment of promising results, namely sensitivity enhancement and the formation of group-type patterns. The method herein proposed could potentially open a new opportunity for the more in-depth knowledge of the unsaponifiable fraction of vegetable oils. 相似文献
42.
Andrea Piazzalunga Vera Bernardoni Paola Fermo Roberta Vecchi 《Analytical and bioanalytical chemistry》2013,405(2-3):1123-1132
In the last decade, our research group set up and optimised analytical techniques for the characterisation of the major components of atmospheric aerosol (i.e. secondary inorganic ions and carbonaceous material) and source markers (e.g. levoglucosan, carbonates). In this study, we present a complete overview on the most problematic aspects that can be encountered during the quantification of the two main components of aerosol, i.e. the ionic and carbonaceous fractions. More in detail, different liquid chromatographic approaches were set up for main ions and anhydrosugars determination. Quality assurance procedures (i.e. tests on data reliability) were applied during the set-up phase and they are presented in this work. As regards the carbonaceous component characterisation, two evolved gas analysis techniques were set up and applied: the thermogravimetric technique coupled to the Fourier transformed infrared spectroscopy (TGA/FTIR) and the thermal–optical transmittance method (TOT). A suitable protocol for organic and elemental carbon separation was set up for the TGA/FTIR system and a comparison with the results obtained by the TOT method was carried out. Studies on the impact of filter load, field blanks, and sample composition on OC/EC quantification by the TOT method were performed. Moreover, approaches for carbonate carbon quantification on different kinds of filters were developed. It was demonstrated that this approach allows to reach the ionic balance in samples impacted by carbonate compounds. The optimised methods have been applied for the analysis of thousands of PM filters allowing the obtainment of reliable results. 相似文献
43.
Augusto Rivera Jaime Ríos-Motta Ginna Paola Trujillo Derly Marcela González Daniel Alcázar 《合成通讯》2013,43(6):791-799
A series of 2,2′-(dihydropyrimidine-1,3(2H,4H)-diyldimethanediyl)bis(substituted-phenols) was synthesized using a Mannich-type reaction between the macrocyclic aminal 1,3,7,9,13,15,19,21-octaazapentacyclo[19.3.1.13,7.19,13.115,19]octacosane (OAPO) (1) and substituted phenols in basic media. These previously unreported compounds were separated from the reaction mixture by column chromatography in highly pure form with 25–75% yields. The most stable conformer was predicted using AM1-type semiempirical quantum chemical calculations. 相似文献
44.
Barbara M. Cellamare Paola Fini Angela Agostiano Salvatore Sortino Pinalysa Cosma 《Photochemistry and photobiology》2013,89(2):432-441
Photodynamic therapy (PDT) is a way of treating malignant tumors and hyperproliferative diseases. It is based on the use of photosensitizer, herein the chlorophyll a (chl a), and a light of an appropriate wavelength. The interaction of the photosensitizer (PS) with the light produces reactive oxygen species (ROS), powerful oxidizing agents, which cause critical damage to the tissue. To solubilize chl a in aqueous solution and to obtain it as monomer, we have used cyclodextrins, carriers which are able to interact with the pigment and form the inclusion complex. The aim of this study is to examine which types of ROS are formed by Chl a/cyclodextrin complexes in phosphate buffered solution and cell culture medium, using specific molecules, called primary acceptors, which react selectively with the reactive species. In fact the changes of the absorption and the emission spectra of these molecules after the illumination of the PS provide information on the specific ROS formation. The 1O2 formation has been tested using chemical methods based on the use of Uric Acid (UA), 9,10‐diphenilanthracene (DPA) and Singlet oxygen sensor green (SOSG) and by direct detection of Singlet Oxygen (1O2) luminescence decay at 1270 nm. Moreover, 2,7‐dichlorofluorescin and ferricytochrome c (Cyt Fe3+) have been used to detect the formation of hydrogen peroxide and superoxide radical anion, which reduces Fe3+ of the ferricytochrome to Fe2+, respectively. 相似文献
45.
Depending on their relative orientation, coupled oscillating carbonyl groups provide a VCD spectrum with a characteristic CO bond stretching region showing a strong bisignate VCD feature, which can be readily predicted adopting long available semiempirical methods. The extended coupled oscillator (ECO) formalism has been used to assign the absolute configuration of a recently synthesized chiral 3-substituted isoindolinone. The prediction of (S) configuration for the (−) enantiomer has been confirmed by quantum mechanical calculations. 相似文献
46.
47.
Cesare Accinelli Anna Barra Caracciolo Paola Grenni 《International journal of environmental analytical chemistry》2013,93(8):579-587
Numerous studies have documented that a wide number of pharmaceuticals used in human and veterinary medicine have the potential to enter the aquatic ecosystem. The antiviral prodrug oseltamivir phosphate has received recent attention with regard to its possible use against the highly pathogenic H5N1 virus. This preliminary laboratory study investigated the persistence of the active antiviral drug, oseltamivir carboxylate (OSC), in water samples taken from an irrigation canal. After an initial rapid decrease, OSC concentrations slowly decreased during the remaining incubation period. Approximately 65% of the initial OSC amount remained in water at the end of the 36-day incubation period. A small amount of OSC was lost both from sterilized water and from sterilized water/sediment samples, suggesting a significant role for microbial degradation. Stimulating microbial processes by the addition of sediments resulted in reduced OSC persistence. Presence of OSC (1.5?µg?mL?1) did not significantly affect the metabolic potential of the water microbial population, estimated by glyphosate and metolachlor mineralization. In contrast, OSC caused an initial transient decrease in the size of the indigenous microbial population of water samples. 相似文献
48.
Rosaria Cozzolino Laura De Magistris Paola Saggese Matteo Stocchero Antonella Martignetti Michele Di Stasio Antonio Malorni Rosa Marotta Floriana Boscaino Livia Malorni 《Analytical and bioanalytical chemistry》2014,406(19):4649-4662
Autism spectrum disorders (ASDs) are a group of neurodevelopmental disorders which have a severe life-long effect on behavior and social functioning, and which are associated with metabolic abnormalities. Their diagnosis is on the basis of behavioral and developmental signs usually detected before three years of age, and there is no reliable biological marker. The objective of this study was to establish the volatile urinary metabolomic profiles of 24 autistic children and 21 healthy children (control group) to investigate volatile organic compounds (VOCs) as potential biomarkers for ASDs. Solid-phase microextraction (SPME) using DVB/CAR/PDMS sorbent coupled with gas chromatography–mass spectrometry was used to obtain the metabolomic information patterns. Urine samples were analyzed under both acid and alkaline pH, to profile a range of urinary components with different physicochemical properties. Multivariate statistics techniques were applied to bioanalytical data to visualize clusters of cases and to detect the VOCs able to differentiate autistic patients from healthy children. In particular, orthogonal projections to latent structures discriminant analysis (OPLS-DA) achieved very good separation between autistic and control groups under both acidic and alkaline pH, identifying discriminating metabolites. Among these, 3-methyl-cyclopentanone, 3-methyl-butanal, 2-methyl-butanal, and hexane under acid conditions, and 2-methyl-pyrazine, 2,3-dimethyl-pyrazine, and isoxazolo under alkaline pH had statistically higher levels in urine samples from autistic children than from the control group. Further investigation with a higher number of patients should be performed to outline the metabolic origins of these variables, define a possible association with ASDs, and verify the usefulness of these variables for early-stage diagnosis. Figure
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49.
Paola Taddei Carla Boga Gabriele Micheletti Barbara Ballarin 《Journal of Raman spectroscopy : JRS》2015,46(1):100-108
Raman and IR spectroscopy were used to investigate the changes induced in yak hair keratin by the straightening treatment based on glyoxylic acid. The amino acidic residues that appeared involved in the reaction with glyoxylic acid were serine and lysine; the involvement of the latter was deduced by the spectroscopic detection of iminic species, resulting from the reaction between the aminic group of lysine and the carbonyl group of glyoxylic acid. The reaction with glyoxylic acid induced conformational rearrangements that mainly involved the fibre bulk rather than the cuticle. Changes in the average tyrosine environment and its hydrogen‐bonding state were detected: at increasing glyoxylic acid incorporation, the tyrosine residues appeared more exposed, probably because of H‐bond interactions with the COOH group. The distribution of the disulfide bridge conformation was also affected, although no cleavage of the S–S bond was detected, in agreement with the shiny and healthy appearance of the fibres. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
50.
Crocetti Letizia Floresta Giuseppe Nazir Shabnam Vergelli Claudia Bhogal Amrit Biancalani Claudio Cesari Nicoletta Giovannoni Maria Paola Cilibrizzi Agostino 《Structural chemistry》2022,33(3):769-793
Structural Chemistry - We report here synthetic approaches to access new classes of small molecules based on three heterocyclic scaffolds, i.e. 3,7-dihydropyrimido[4,5-d]pyridazine-4,8-dione,... 相似文献