A comprehensive gas chromatography system with flow modulation under vacuum conditions

The 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)

Development of a theoretical model to predict retention times in gas chromatography

The Chimic projec

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

This 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)

Determination of aromatic sulphur compounds in heavy gas oil by using (low-)flow modulated comprehensive two-dimensional gas chromatography–triple quadrupole mass spectrometry

The present research is focused on the development of a flow-modulated comprehensive two-dimensional gas chromatography-triple quadrupole mass spectrometry (FM GC. ×. GC-MS/MS) method for the determination of classes of aromatic organic sulphur compounds (benzothiophenes, dibenzothiophenes, and benzonaphthothiophene) in heavy gas oil (HGO). The MS/MS instrument was used to provide both full-scan and multiple-reaction-monitoring (MRM) data. Linear retention index (LRI) ranges were used to define the MRM windows for each chemical class. Calibration solutions (internal standard: 1-fluoronaphthalene) were prepared by using an HGO sample, depleted of S compounds. Calibration information was also derived for the thiophene class (along with MRM and LRI data), even though such constituents were not present in the HGO. Linearity was satisfactory over the analyzed concentration range (1-100. mg/L); intra-day precision for the lowest calibration point was always below 17%. Accuracy was also satisfactory, with a maximum percentage error of 3.5% (absolute value) found among the S classes subjected to (semi-)quantification. The highest limit of quantification was calculated to be 299. μg/L (for the C1-benzothiophene class), while the lowest was 21. μg/L (for the C4-benzothiophene class)

Recent developments in the high-throughput separation of biologically active chiral compounds via high performance liquid chromatography

: Bioactive compounds, including active pharmaceutical ingredients (APIs), are often chiral molecules where stereoisomers have different biological and therapeutic activity. Nevertheless, the preparation of these molecules can lead to racemic or scalemic mixtures (it is not trivial to produce just the optically pure compound). The evaluation of the enantiomeric purity of bioactive compounds, and therefore quality, is indeed of fundamental importance for regulatory scopes. Chiral high performance liquid chromatography (HPLC) is the gold standard technique to separate and to purify enantiomers. This comes from the wide availability of commercial chiral stationary phases (CSPs) and operational modes, which makes the technique extremely versatile. In recent years, the most relevant trend in the field of chiral analytical HPLC has been the development of CSPs suitable for fast or even ultrafast separations, thus favoring the high throughput screening of biologically active chiral compounds. This process has somehow lagged behind compared to achiral HPLC, due to a series of practical and fundamental issues. The experience has shown how in chiral chromatography even very basic concepts, such as the supposed kinetic superiority of core-shell (pellicular) particles over fully porous ones to improve the chromatographic efficiency, cannot be taken for granted. In this review, the most relevant fundamental and practical features that must be taken into consideration to design successful high-throughput, fast enantioseparations will be discussed. Afterwards, the main classes of CSPs and the most relevant, recent (last five-year) high-throughput applications in the field of the separation of chiral bioactive compounds (for pharmaceutical, forensic, food, and omics applications) will be considered