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101.
102.
Eduardo Sommella Giacomo Pepe Francesco Pagano Gian Carlo Tenore Paola Dugo Michele Manfra Pietro Campiglia 《Journal of separation science》2013,36(20):3351-3355
We have developed a fast ultra HPLC with ion‐trap TOF‐MS method for the analysis of flavonoids in Citrus bergamia juice. With respect to the typical methods for the analysis of these matrices based on conventional HPLC techniques, a tenfold faster separation was attained. The use of a core–shell particle column ensured high resolution within the fast analysis time of only 5 min. Unambiguous determination of flavonoid identity was obtained by the employment of a hybrid ion‐trap TOF mass spectrometer with high mass accuracy (average error 1.69 ppm). The system showed good retention time and peak area repeatability, with maximum RSD% values of 0.36 and 3.86, respectively, as well as good linearity (R2 ≥ 0.99). Our results show that ultra HPLC can be a useful tool for ultra fast qualitative/quantitative analysis of flavonoid compounds in citrus fruit juices. 相似文献
103.
Dr. Annalisa Mancini Dr. M. Carla Aragoni Dr. Neil Bricklebank Dr. Carlo Castellano Prof. Francesco Demartin Prof. Francesco Isaia Prof. Vito Lippolis Dr. Anna Pintus Dr. Massimiliano Arca 《化学:亚洲杂志》2013,8(3):639-647
The reactions of 4,5,6,7‐tetrathiocino‐[1,2‐b:3,4‐b′]‐1,3,8,10‐tetrasubstituted‐diimidazolyl‐2,9‐dithiones (R2,R′2‐todit; 1 : R=R′=Et; 2 : R=R′=Ph; 3 : R=Et, R′=Ph) with Br2 exclusively afforded 1:1 and 1:2 “T‐shaped” adducts, as established by FT‐Raman spectroscopy and single‐crystal X‐ray diffraction in the case of complex 1? 2 Br2. On the other hand, the reactions of compounds 1 – 3 with molecular I2 provided charge‐transfer (CT) “spoke” adducts, among which the solvated species 3? 2 I2 ? (1?x)I2 ? x CH2Cl2 (x=0.94) and ( 3 )2 ? 7 I2 ? x CH2Cl2, (x=0.66) were structurally characterized. The nature of all of the reaction products was elucidated based on elemental analysis and FT‐Raman spectroscopy and supported by theoretical calculations at the DFT level. 相似文献
104.
The stereocontrolled condensation of methyl ketones to trans α,β‐aziridine aldehydes creates functionalized aldols, valuable precursors for different amino hydroxylated structures, such as amino alcohols, amino diols, α‐tetrahydrofuryl amides, and α‐furyl amides. 相似文献
105.
QuEChERS sample preparation for the determination of pesticides and other organic residues in environmental matrices: a critical review 总被引:4,自引:0,他引:4
Maria Concetta Bruzzoniti Leonardo Checchini Rosa Maria De Carlo Serena Orlandini Luca Rivoira Massimo Del Bubba 《Analytical and bioanalytical chemistry》2014,406(17):4089-4116
Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) is an extraction and clean-up technique originally developed for recovering pesticide residues from fruits and vegetables. Since its introduction, and until December 2013, about 700 papers have been published using the QuEChERS technique, according to a literature overview carried out using SciFinder, Elsevier SciVerse, and Google search engines. Most of these papers were dedicated to pesticide multiresidue analysis in food matrices, and this topic has been thoroughly reviewed over recent years. The QuEChERS approach is now rapidly developing beyond its original field of application to analytes other than pesticides, and matrices other than food, such as biological fluids and non-edible plants, including Chinese medicinal plants. Recently, the QuEChERS concept has spread to environmental applications by analyzing not only pesticides but also other compounds of environmental concern in soil, sediments, and water. To the best of our knowledge, QuEChERS environmental applications have not been reviewed so far; therefore, in this contribution, after a general discussion on the evolution and changes of the original QuEChERS method, a critical survey of the literature regarding environmental applications of conventional and modified QuEChERS methodology is provided. The overall recoveries obtained with QuEChERS and other extraction approaches (e.g., accelerated solvent extraction, ultrasonic solvent extraction, liquid/solid extraction, and soxhlet extraction) were compared, providing evidence for QuEChERS higher recoveries for various classes of compounds, such as biopesticides, chloroalkanes, phenols, and perfluoroalkyl substances. The role of physicochemical properties of soil (i.e., clay and organic carbon content, as well as cation exchange capacity) and target analytes (i.e., log KOW, water solubility, and vapor pressure) were also evaluated in order to interpret recovery and matrix effect data. 相似文献
106.
Vnia S. F. Muralha Sara Canaveira Jos Miro Susana Coentro Teresa Morna Carlo Stefano Salerno 《Journal of Raman spectroscopy : JRS》2015,46(5):483-492
For the first time, 18th‐century glass mosaics from the Capela de São João Baptista (Chapel of St. John the Baptist, Lisbon) were analysed by Raman microscopy (RM). This masterpiece in baroque mosaic art had one of its major contributors the most famous glassmaker in Rome, Alessio Mattioli. Mattioli was celebrated because of the opacity of his mosaics and the astonishing number of hues he was able to produce for mosaic decorating Saint Peter's Basilica in Rome. This study had two goals in mind: (1) characterising the materials involved in the manufacture of these glass mosaics and (2) lengthening the understanding of what was left of Mattioli's glassmaking records. As expected the mosaics presented a high ratio of crystalline phases, making RM the ideal technique for non‐destructive analysis. The mosaics contained a white ‘background’ or opacifier added identified as Ca2Sb2O7. The yellow tesserae are opacified with lead antimonate (Pb2Sb2O7) and ternary oxides, structures related to lead antimonate but with other ions entering the position of Sb4+ (namely Sn4+). Those ternary oxides are pervasive in most colours, admixed with other colorants. The red, orange, pink and brown colours were accomplished with cuprous oxide (Cu2O) and admixed with a ternary oxide to create the latter three colours. The red copper‐based colours were made according to the procedure to make a ruby copper glass and with the exception of the red colour; all mosaics exhibited a dark layer on each side of the mosaic, named scorzetta. This layer is the outcome of an oxidation reaction because of a quick cooling process and is composed of CuO. Finally the blue and green colours are accomplished with cobalt oxide and copper oxide, respectively, and the purple/black colour with manganese oxide. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
107.
Irena Zupanič Pajnič Carlo Previderè Tomaž Zupanc Martina Zanon Paolo Fattorini 《Electrophoresis》2022,43(13-14):1521-1530
The recent introduction of polymerase chain reaction (PCR)-massively parallel sequencing (MPS) technologies in forensics has changed the approach to allelic short tandem repeat (STR) typing because sequencing cloned PCR fragments enables alleles with identical molecular weights to be distinguished based on their nucleotide sequences. Therefore, because PCR fidelity mainly depends on template integrity, new technical issues could arise in the interpretation of the results obtained from the degraded samples. In this work, a set of DNA samples degraded in vitro was used to investigate whether PCR-MPS could generate “isometric drop-ins” (IDIs; i.e., molecular products having the same length as the original allele but with a different nucleotide sequence within the repeated units). The Precision ID GlobalFiler NGS STR panel kit was used to analyze 0.5 and 1 ng of mock samples in duplicate tests (for a total of 16 PCR-MPS analyses). As expected, several well-known PCR artifacts (such as allelic dropout, stutters above the threshold) were scored; 95 IDIs with an average occurrence of 5.9 IDIs per test (min: 1, max: 11) were scored as well. In total, IDIs represented one of the most frequent artifacts. The coverage of these IDIs reached up to 981 reads (median: 239 reads), and the ratios with the coverage of the original allele ranged from 0.069 to 7.285 (median: 0.221). In addition, approximately 5.2% of the IDIs showed coverage higher than that of the original allele. Molecular analysis of these artifacts showed that they were generated in 96.8% of cases through a single nucleotide change event, with the C > T transition being the most frequent (85.7%). Thus, in a forensic evaluation of evidence, IDIs may represent an actual issue, particularly when DNA mixtures need to be interpreted because they could mislead the operator regarding the number of contributors. Overall, the molecular features of the IDIs described in this work, as well as the performance of duplicate tests, may be useful tools for managing this new class of artifacts otherwise not detected by capillary electrophoresis technology. 相似文献
108.
M. R. Ajayakumar Marco Di Giovannantonio Carlo A. Pignedoli Lin Yang Pascal Ruffieux Ji Ma Roman Fasel Xinliang Feng 《Journal of polymer science. Part A, Polymer chemistry》2022,60(12):1912-1917
The precise introduction of nonplanar pores in the backbone of graphene nanoribbon represents a great challenge. Here, we explore a synthetic strategy toward the preparation of nonplanar porous graphene nanoribbon from a predesigned dibromohexabenzotetracene monomer bearing four cove-edges. Successive thermal annealing steps of the monomers indicate that the dehalogenative aryl-aryl homocoupling yields a twisted polymer precursor on a gold surface and the subsequent cyclodehydrogenation leads to a defective porous graphene nanoribbon containing nonplanar [14]annulene pores and five-membered rings as characterized by scanning tunneling microscopy and noncontact atomic force microscopy. Although the C–C bonds producing [14]annulene pores are not achieved with high yield, our results provide new synthetic perspectives for the on-surface growth of nonplanar porous graphene nanoribbons. 相似文献
109.
Simone Madama Ermelinda Falletta Amir Mohammad Malvandi Kevin Arzoni Carlo Brogna Marco Varelli Matteo Bertelli Matteo Conti Martina Larini Federico Guidugli Pietro Traldi Simone Cristoni 《Journal of mass spectrometry : JMS》2022,57(8):e4876
In this work, the isolation step in the linear ion trap was performed using different “q values” conditions at a low collision-induced dissociation (CID) energy leading to the parent ion resolution improvements, reasonably due to better ion energy distribution. According to the results, we obtained a greater resolution and mass accuracy operating in both traditional electrospray and low voltage ionization near the q value = 0.778 and with a CID energy of 10%. This effect was evaluated with low-molecular-mass compounds (skatole and arginine). The proposed optimization yielded a superior instrument performance without adding technological complexity to mass spectrometry analyses. 相似文献
110.
Spin foam models are hoped to provide the dynamics of loop-quantum gravity. However, the most popular of these, the Barrett-Crane model, does not have the good boundary state space and there are indications that it fails to yield good low-energy n-point functions. We present an alternative dynamics that can be derived as a quantization of a Regge discretization of Euclidean general relativity, where second class constraints are imposed weakly. Its state space matches the SO(3) loop gravity one and it yields an SO(4)-covariant vertex amplitude for Euclidean loop gravity. 相似文献