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排序方式: 共有225条查询结果,搜索用时 31 毫秒
31.
Greta Petrella Camilla Montesano Sara Lentini Giorgia Ciufolini Domitilla Vanni Roberto Speziale Andrea Salonia Francesco Montorsi Vincenzo Summa Riccardo Vago Laura Orsatti Edith Monteagudo Daniel Oscar Cicero 《Molecules (Basel, Switzerland)》2021,26(14)
A new strategy that takes advantage of the synergism between NMR and UHPLC–HRMS yields accurate concentrations of a high number of compounds in biofluids to delineate a personalized metabolic profile (SYNHMET). Metabolite identification and quantification by this method result in a higher accuracy compared to the use of the two techniques separately, even in urine, one of the most challenging biofluids to characterize due to its complexity and variability. We quantified a total of 165 metabolites in the urine of healthy subjects, patients with chronic cystitis, and patients with bladder cancer, with a minimum number of missing values. This result was achieved without the use of analytical standards and calibration curves. A patient’s personalized profile can be mapped out from the final dataset’s concentrations by comparing them with known normal ranges. This detailed picture has potential applications in clinical practice to monitor a patient’s health status and disease progression. 相似文献
32.
Carmela Maria Montone Michela Antonelli Anna Laura Capriotti Chiara Cavaliere Giorgia La Barbera Susy Piovesana Aldo Lagan 《Journal of separation science》2019,42(10):1938-1947
An analytical method for determining seleno‐methionine, methyl‐seleno‐cysteine, and seleno‐cystine in wheat bran was developed and validated. Four different extraction procedures were evaluated to simultaneously extract endogenous free and conjugated seleno‐amino acids in wheat bran in order to select the best extraction protocol in terms of seleno amino acid quantitation. The extracted samples were subjected to a clean‐up by a reversed phase/strong cation exchange solid‐phase extraction and analyzed by chiral hydrophilic interaction liquid chromatography‐tandem mass spectrometry. The optimized extraction protocol was employed to validate the methodology. Process efficiency ranged from 58 to 112% and trueness from 73 to 98%. Limit of detection and limit of quantification were lower than 1 ng/g. Four wheat bran samples were analyzed for both total Se and single seleno‐amino acids determination. The results showed that Se‐ seleno‐methyl‐l selenocysteine was the major seleno‐amino acid in wheat bran while seleno‐methionine and seleno‐cysteine were both minor species. 相似文献
33.
Alesi S Brancolini G Melucci M Capobianco ML Venturini A Camaioni N Barbarella G 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(2):513-521
Quaterthiophene-dinucleotide conjugates 5'TA3'-t4-3'AT5', 5'AA3'-t4-3'AA5', and 5'TT3'-t4-3'TT5' (TA: thymidine-adenosine, AA: adenosine-adenosine, TT: thymidine-thymidine) were synthesized and analyzed by a combination of spectroscopy and microscopy, electrical characterization, and theoretical calculations. Circular dichroism (CD) experiments demonstrated a transfer of chirality from the dinucleotides to quaterthiophene at high ionic strength and in cast films. The films were photoluminescent and electroactive. CD and photoluminescence spectra and current density/voltage plots (measured under dynamic vacuum) displayed significant variation on changing the dinucleotide scaffold. Molecular mechanics and molecular dynamics calculations indicated that the conformation and packing modes of the conjugates are the result of a balance between intra- and intermolecular nucleobase-thiophene stacking interactions and intramolecular hydrogen bonding between the nucleobases. 相似文献
34.
Mycoestrogen determination in cow milk: Magnetic solid‐phase extraction followed by liquid chromatography and tandem mass spectrometry analysis
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Anna Laura Capriotti Chiara Cavaliere Patrizia Foglia Giorgia La Barbera Roberto Samperi Salvatore Ventura Aldo Laganà 《Journal of separation science》2016,39(24):4794-4804
Recently, magnetic solid‐phase extraction has gained interest because it presents various operational advantages over classical solid‐phase extraction. Furthermore, magnetic nanoparticles are easy to prepare, and various materials can be used in their synthesis. In the literature, there are only few studies on the determination of mycoestrogens in milk, although their carryover in milk has occurred. In this work, we wanted to develop the first (to the best of our knowledge) magnetic solid‐phase extraction protocol for six mycoestrogens from milk, followed by liquid chromatography and tandem mass spectrometry analysis. Magnetic graphitized carbon black was chosen as the adsorbent, as this carbonaceous material, which is very different from the most diffuse graphene and carbon nanotubes, had already shown selectivity towards estrogenic compounds in milk. The graphitized carbon black was decorated with Fe3O4, which was confirmed by the characterization analyses. A milk deproteinization step was avoided, using only a suitable dilution in phosphate buffer as sample pretreatment. The overall process efficiency ranged between 52 and 102%, whereas the matrix effect considered as signal suppression was below 33% for all the analytes even at the lowest spiking level. The obtained method limits of quantification were below those of other published methods that employ classical solid‐phase extraction protocols. 相似文献
35.
Six flavonol glycosides were isolated and identified from the aerial parts of Anthyllis barba-jovis L. (Leguminosae), together with two coumarins and D-pinitol, a taxonomic marker of Leguminosae family. The structural elucidation of all compounds was based on their (1)H- and (13)C-NMR spectral data and bidimensional experiments. The total flavonoid content was also determined, according to the method described in the Italian pharmacopoeia. In order to complete the phytochemical investigation on A. barba-jovis, the essential oils from flowers and seeds were obtained by hydrodistillation and analysed by GC-MS; fresh flowers were analysed also directly by solid phase micro extraction (SPME). 相似文献
36.
37.
Peter Quinto Tranchida Giorgia Purcaro Lanfranco Conte Paola Dugo Giovanni Dugo Luigi Mondello 《Journal of chromatography. A》2009,1216(43):7301-7306
The present research is based on the full exploitation of the separation power of a 0.05 mm internal diameter (ID) capillary, as a comprehensive two-dimensional (2D) GC (GC × GC) secondary column, with the objective of attaining very high-resolution second dimension separations. The aim was achieved by using a split-flow system developed in previous research [P.Q. Tranchida, A. Casilli, P. Dugo, G. Dugo, L. Mondello, Anal. Chem. 79 (2007) 2266], and a dual-oven GC × GC instrument. The column combination employed consisted of a polar 30 m × 0.25 mm ID column connected, by means of a T union, to a detector-linked high-resolution 1.1 m × 0.05 mm ID apolar analytical column and to a 0.33 m × 0.05 mm ID retention gap; the latter was connected to a manually operated split valve. As previously demonstrated, the use of a split valve enables the regulation of gas flows through both analytical columns, generating the most appropriate gas linear velocities. Comprehensive 2D GC experiments were carried out on Arabica roasted coffee volatiles (previously extracted by means of solid-phase microextraction) with the split-valve closed (equal to what can be defined as conventional GC × GC) and with the split-valve opened at various degrees. The reasons why it is absolutely not effective to use a 0.05 mm ID column as second dimension in a conventional GC × GC instrument will be discussed and demonstrated. On the contrary, the use of a 0.05 mm ID column as second dimension, under ideal conditions in a split-flow, twin-oven system, will also be illustrated and discussed. 相似文献
38.
Laurent Hollecker Maurizio Pinna Giorgia Filippino Stefania Scrugli Barbara Pinna Francesca Argiolas Mariano Murru 《Journal of chromatography. A》2009,1216(15):3402-3408
A new method for the identification and the quantification of nonanthocyanin phenolic compounds from six Vitis Vinifera grape varieties native to Sardinia (three native: Vermentino, Malvasia and Cannonau and three non-native types: Chardonnay, Sauvignon and Cabernet Sauvignon; Argiolas vineyard) was developed. This rapid and selective method employs LC/ESI-MS in negative mode. Different solvents extraction and different sorbents for purification were compared to the direct analysis of the initial extracts without further sample preparation. A total of 54 phenolic compounds were identified either in the freeze-dried skins or seeds, including nonflavonoids (hydroxybenzoic and hydroxycinnamic acids and their derivatives, stilbenes) and flavonoids (flavanols, flavonols, dihydroxyflavonols). 相似文献
39.
Elsebeth L. Kendix Silvia Prati Edith Joseph Giorgia Sciutto Rocco Mazzeo 《Analytical and bioanalytical chemistry》2009,394(4):1023-1032
In the field of FTIR spectroscopy, the far infrared (FIR) spectral region has been so far less investigated than the mid-infrared
(MIR), even though it presents great advantages in the characterization of those inorganic compounds, which are inactive in
the MIR, such as some art pigments, corrosion products, etc. Furthermore, FIR spectroscopy is complementary to Raman spectroscopy
if the fluorescence effects caused by the latter analytical technique are considered. In this paper, ATR in the FIR region
is proposed as an alternative method to transmission for the analyses of pigments. This methodology was selected in order
to reduce the sample amount needed for analysis, which is a must when examining cultural heritage materials. A selection of
pigments have been analyzed in both ATR and transmission mode, and the resulting spectra were compared with each other. To
better perform this comparison, an evaluation of the possible effect induced by the thermal treatment needed for the preparation
of the polyethylene pellets on the transmission spectra of the samples has been carried out. Therefore, pigments have been
analyzed in ATR mode before and after heating them at the same temperature employed for the polyethylene pellet preparation.
The results showed that while the heating treatment causes only small changes in the intensity of some bands, the ATR spectra
were characterized by differences in both intensity and band shifts towards lower frequencies if compared with those recorded
in transmission mode. All pigments' transmission and ATR spectra are presented and discussed, and the ATR method was validated
on a real case study.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
40.
Ali Shahpari Abdelgader Abdalla Ricardo Ferreira Giorgia Parca Jacklyn D. Reis Mario Lima 《Fiber and Integrated Optics》2014,33(3):149-162
AbstractThis article experimentally demonstrates a hybrid fiber–free-space passive optical network that enables high spectral density, aggregated capacity, and total throughput through ultra-dense wavelength-division multiplexing baseband and radio-over-fiber channels. Ultra-dense wavelength-division multiplexing 10-Gb/s Nyquist-shaped 16-ary quadrature amplitude modulation, 10-Gb/s radio-over-fiber orthogonal frequency-division multiplexing, and 8.75-Gb/s baseband orthogonal frequency-division multiplexing signals per user were transmitted through a maximum 40-km passive optical network, which includes a 6-m free-space optics link with acceptable performance. 相似文献