1,720,974 research outputs found
A comprehensive gas chromatography system with flow modulation under vacuum conditions
No full textThe invention relates to the exploitation of low pressure conditions in the second analytical dimension of flow-modulated comprehensive two-dimensional gas chromatography (GCxGC) systems to reduce the requirements of high gas flows exiting the modulator. The invention specifically relates to flow modulators (3) characterized by the necessity of high gas flows (e.g.,>10 mL/min), to efficiently release effluent accumulated from the first column (12), onto the second column (20). The use of a second analytical column (20), with an internal diameter (ID) equal to, or exceeding 0.30 mm (e.g., 0.32 mm, 0.53 mm), along with vacuum outlet conditions, reduces the pressure conditions inside the second analytical column. Such intra-column low pressure conditions enables efficient release of effluent from the modulator, using lower gas flows (e.g., 7-8 mL/min)
Comprehensive two-dimensional gas chromatography-mass spectrometry: Recent evolution and current trends
No full textpeer reviewe
Flow modulation comprehensive two-dimensional gas chromatography-mass spectrometry using ≈ 4 mL min-1 gas flows
No full textpeer reviewe
(Low-)flow modulation comprehensive two-dimensional gas chromatography for the determination of suspected allergens in fragrances
No full textUse of solid-phase micro extraction (SPME) for determination of mineral oil and polycyclic aromatic hydrocarb0ns by mono dimensional GC or GCxGC
No full textSolid-phase microextraction (SPME) is a rapid, easy and solvent-free or low-solvent consuming technique. Several kind of different fibers are available commercially, thus the most suitable selectivity may be chosen according to the specific application. In the present work, the potential of a particular and low exploited fiber (carbopack Z/PDMS) was investigated for determination of mineral oil (MO) and polycyclic aromatic hydrocarbons (PAHS) in foods. The prevalent sorption mechanism of the carbopack Z/PDMS fiber depends on the extraction conditions. In a non-polar solvent the effect of carbopack Z is predominant, which is particularly prone to the extraction of planar compounds by π- π interaction. While sampling the head-space (HS) the sorption mechanism of the PDMS predominates. Therefore, two independent approaches were studied, one using the direct-immersion (DI) extraction, the other by HS-SPME to exploit the carbopack Z and the PDMS selectivity, respectively.
A method to analyze parent PAHs was developed by direct immersion of the fiber in a hexane solution, following by GC-MS analysis for the determination of benzo[a]pyrene, or by comprehensive GC (GCxGC) coupled to time-of-flight (ToF) MS detector for the determination of the 16 PAHs highlighted by the European Union. Very good repeatability, limit of detection (LOD), and limit of quantification (LOQ) values were obtained.
The same fiber was employed to sampling the HS of food samples, thus exploiting, as prevalent sorption mechanism, the PDMS affinity. A good selectivity for MO components was observed, thus a rapid screening method was developed with satisfactory results
Benefits of using High-Performance Liquid Chromatography pre/separation step, prior to comprehensive two/dimensional gas chromatography-mass spectrometrmetry essential oil analysis
No full textAdvanced multidimensional gas chromatographic techniques coupled to mass spectrometry for the analysis of the saponifiable and unsaponifiable fractions of lipids
No full textPotential of comprehensive chromatography in food analysis
No full textThe outstanding selectivity and sensitivity of specific comprehensive two-dimensional chromatography (C2DC) methodologies (particularly with mass-spectrometry detection) have made feasible trace (ppb level), and ultra-trace (ppt level and lower) analysis of target compounds, reducing the need for tedious sample-preparation processes.The present review can be considered a continuation of a review published in 2004 [J. Chromatogr., A 1054 (2004) 3]. Rather than an exhaustive description of the C2DC food applications since then, we provide detailed critical descriptions of significant changes and applications. © 2013 Elsevier Ltd
Flow-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)
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