1,720,961 research outputs found
Low-flow modulation comprehensive 2D GC-high resolution ToF MS: a powerful tool for untargeted, pre- and post-targeted analysis
No full textFlow-modulated Comprehensive Two-dimensional Gas Chromatography-Triple Quadrupole Mass Spectrometry Elucidation of the Fatty Acids and Unsaponoable Constituents of Oil Derived from Lemon Seeds, A Food-Industry Waste Producy
No full textThis article is focused on the detailed qualitative analysis of the fatty
acids and the unsaponifiable constituents of a vegetable oil derived
from a food-industry waste product, namely lemon seeds. The seed oil
was subjected to two sample preparation processes, the first enabling
the formation of fatty acid methyl esters (FAMEs), and the other the
isolation of the constituents of the entire unsaponifiable fraction (sterols,
hydrocarbons, vitamins, etc.). Both sets of compounds were subjected to
flow-modulation comprehensive two-dimensional gas chromatography–
mass spectrometry (GC×GC–MS), with identification performed through
full-scan data. Relative percentage data, relative to FAMEs and sterols,
were derived through gas chromatography–flame ionization (GC–FID).
Finally, a sterol identified through a clear signal as cholesterol, was
subjected to absolute quantification using multiple reaction monitoring
(MRM)
Advanced multidimensional gas chromatographic techniques coupled to mass spectrometry for the analysis of the saponifiable and unsaponifiable fractions of lipids
No full textFlow-modulated comprehensive two-dimensional gas chromatography combined with a high-resolution time-of-flight mass spectrometer: A proof-of-principle study
No full textpeer reviewe
Analysis of human plasma lipids by using comprehensive two‐dimensional gas chromatography with dual detection and with the support of high‐resolution time‐of‐flight mass spectrometry for structural elucidation
No full textThe main focus of the present research is the analysis of the unsaponifiable lipid fraction of human plasma by using data derived from comprehensive two-dimensional gas chromatography with dual quadrupole mass spectrometry and flame ionization detection. This approach enabled us to attain both mass spectral information and analyte percentage data. Furthermore, gas chromatography coupled with high-resolution time-of-flight mass spectrometry was used to increase the reliability of identification of several unsaponifiable lipid constituents. The synergism between both the high-resolution gas chromatography and mass spectrometry processes enabled us to attain a more in-depth knowledge of the unsaponifiable fraction of human plasma. Additionally, information was attained on the fatty acid and triacylglycerol composition of the plasma samples, subjected to investigation by using comprehensive two-dimensional gas chromatography with dual quadrupole
mass spectrometry and flame ionization detection and high-performance liquid chromatography with atmospheric pressure chemical ionization quadrupole mass spectrometry, respectively
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
) seed by comprehensive two‐dimensional gas chromatography with flame ionization/mass spectrometry detection and non‐aqueous reversed‐phase liquid chromatography with atmospheric pressure chemical ionization mass spectrometry detection
No full textA chemical characterization of major lipid components, namely, triacylglycerols, fatty acids and the unsaponifiable fraction, in a Quinoa seed lipids sample is reported. To tackle such a task, non-aqueous reversed-phase high-performance liquid chromatography with mass spectrometry detection was employed. The latter was interfaced with atmospheric pressure chemical ionization for the analysis of triacylglycerols. The main triacylglycerols (>10%) were represented by OLP, OOL and OLL (P = palmitoyl, O = oleoyl, L = linoleoyl); the latter was present in the oil sample at the highest percentage (18.1%). Furthermore, fatty acid methyl esters were evaluated by gas chromatography with flame ionization detection. 89% of the total fatty acids was represented by unsaturated fatty acid methyl esters with the greatest percentage represented by linoleic and oleic acids accounting for approximately 48 and 28%, respectively. An extensive characterization of the unsaponifiable fraction of Quinoa seed lipids was performed for the first time, by using comprehensive two-dimensional gas chromatography with dual mass spectrometry/flame ionization detection. Overall, 66 compounds of the unsaponifiable fraction were tentatively identified, many constituents of which (particularly sterols) were confirmed by using gas chromatography with high-resolution time-of-flight mass spectrometry
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