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Characterization of Phyto-Constituents
Published in Rohit Dutt, Anil K. Sharma, Raj K. Keservani, Vandana Garg, Promising Drug Molecules of Natural Origin, 2020
Himangini, Faizana Fayaz, Anjali
GC-MS is the aggregate of two effective device Gas spectrometry and Mass chromatography which is the most delicate and particular method and gives data on the molecular weight as well as the compound structure. In MS, it depends upon ionization of molecule and then separate the ions. The methods of ionization integrated with GD are electron impact (EI) and electron capture ionization (ECI) method. Electron Ionization specifically pulls in towards positive ions, while ECI is utilized for negative ions (ECNI).
Exposure Assessment
Published in Samuel C. Morris, Cancer Risk Assessment, 2020
Having thus demolished the concept of index compounds, only one reason remains to justify their use: there is generally no practical alternative. Complete characterization of the mixture with gas chromatography/-mass spectrometry (GC/MS) is time-consuming, expensive, and, perhaps most importantly, produces a result as complex as the mixture itself, thus defying the comparison of different mixtures. The only practical solution appears to be to use an index, but when comparing different mixes, to fall-back on an ad hoc comparison of the GC/MS scan as a means of tempering the use of the index with some idea of uncertainty. Current thinking would seem to tend toward use of the aggregate indices such as benzene soluble organics for this purpose. Perhaps this might be coupled with additional information from short-term bioassays (see Chap. 10) and a quantitative factor developed to modify the index value. This remains an area open to both long-term basic research and to development of practical solutions.
Omics and perinatal medicinePreeclampsia
Published in Moshe Hod, Vincenzo Berghella, Mary E. D'Alton, Gian Carlo Di Renzo, Eduard Gratacós, Vassilios Fanos, New Technologies and Perinatal Medicine, 2019
Piya Chaemsaithong, Liona C. Poon
Metabolites are part of primary and intermediate metabolism and are estimated to be represented by more than 114,000 compounds in the human metabolome (171). They are the intracellular molecules that undergo transformation when metabolized and, in effect, provide a blueprint log of its cellular biochemistry. Metabolomics is the detection and semiquantitation of low molecular weight metabolites present in cells, tissues, or body fluids, using proton nuclear magnetic resonance (1H-NMR) spectroscopy or mass spectrometry (gas chromatography [GC] and liquid chromatography-mass spectrometry [LC-MS] based). NMR technique detects metabolites based on the magnetic properties of atomic nuclei and is highly reproducible and a nondestructive approach, which requires minimal sample preparation (172). Disadvantages of NMR technique include overlapping signals and low sensitivity compared to MS methods (173). In contrast, the MS method uses ionization and fragmentation for detection of metabolites. GC-MS methods require extensive sample preparation and are time consuming and expensive. The LC-MS approach is aimed at detecting both hydrophilic and hydrophobic metabolites with high sensitivity, and has a small sample volume requirement and less extensive sample preparation compared to GC-MS (173,174). However, the small LC-MS database for identification of protein is a major limitation.
Evaluation of anti-scorpion (Hottentota tamulus) venom potential of native plants extracts using mice model
Published in Toxin Reviews, 2022
Samima Asad Butt, Hafiz Muhammad Tahir, Shaukat Ali, Muniba Tariq, Ali Hassan, Muhammad Summer, Chand Raza, Shafaat Yar Khan
Gas chromatography-mass spectrometry (GC-MS) is a laboratory technique that involves separation properties of gas-liquid chromatography with the feature of detection by mass-spectrometry to identify various substances within a test sample. GC-MS is used to separate the volatile substances in sample while MS refers to their identification on the basis of their mass. For GC-MS the vapor pressure of analyte should be between 30 and 300 °C. GC-MS offers the identification based on retention time matching that may be incorrect. GC-MS shows the mass of given particle (z) to the number of electrostatic charges (e). GC-MS commonly uses chemical ionization (CI) and electron impact (EI) techniques (Chauhan et al. 2014). The parameters used in GC-MS analysis were Retention time (RT), I Time, F Time, Area, Area %, Height, Height %, A/H and Base m/z.
Overview of analytical methods for determining novel psychoactive substances, drugs and their metabolites in biological samples
Published in Critical Reviews in Toxicology, 2022
Jadwiga Musiał, Jakub Czarny, Renata Gadzała-Kopciuch
GC–MS is characterized by a lower detection limit than immunochemical tests (Papoutsis et al. 2010; Kerrigan, Banuelos, et al. 2011; Kerrigan, Mellon, et al. 2011). However, GC–MS requires a derivatization step to identify a higher number of psychoactive substances (Papoutsis et al. 2010). Derivatization prolongs run time and increases analytical costs, which poses an additional problem for toxicology laboratories. Due to these shortcomings, LC–MS methods are more widely used than GC–MS (Mueller et al. 2005; Wohlfarthet al. 2010; Dalsgaard et al. 2012; Kneisel and Auwärter 2012; Swortwood et al. 2013; Tang et al. 2014; Wicka et al. 2014; Adamowicz and Tokarczyk 2016; Cannaert et al. 2016; Rojek et al. 2017; Salomone et al. 2017; Yeter 2017; Fels et al. 2020). LC–MS supports the determination of numerous compounds (Mueller et al. 2005; Delsgaard et al. 2012; Tang et al. 2014; Adamowicz and Tokarczyk 2016; Yeter 2017). These methods are characterized by lower LOD values, shorter run time, and lower costs. The optimal method for detecting psychoactive substances should eliminate deuterated compounds which increase the cost of the analysis. Particular focus should be placed on chromatographic methods that enable the separation and subsequent determination of substances with the same m/z ratios. Such analytes cannot be identified by multiple reaction monitoring (MRM) alone without proper chromatographic separation of the analyzed substances.
Bioactive compounds and therapeutic role of Brassica oleracea L. seeds in rheumatoid arthritis rats via regulating inflammatory signalling pathways and antagonizing interleukin-1 receptor action
Published in Biomarkers, 2021
Manal A. Hamed, Asmaa F. Aboul Naser, Mona E. Aboutabl, Abeer F. Osman, Entesar E. S. Hassan, Wessam M. Aziz, Wagdy K. B. Khalil, Ayman A. Farghaly, Ali M. El-Hagrassi
The GC/MS analysis was carried out for unsaponifiable matters using the following conditions; using a Thermo Scientific, Trace GC Ultra/ISQ Single Quadrupole MS, TG-5MS fused silica capillary column (30 m, 0.251 mm, 0.1 mm film thickness). For GC/MS detection, an electron ionization system with ionization energy of 70 eV was used, Helium gas was used as the carrier gas at a constant flow rate of 1 mL/min. The injector and MS transfer line temperature was set at 280 °C. (For unsap). For FAMEs condition, the oven temperature was programmed at an initial temperature 50 °C (hold 2 min) to150 °C at an increasing rate of 7 °C/min, then to 270 at an increasing rate 5 °C/min (hold 2 min) then to 310 as a final temperature at an increasing rate of 3.5 °C/min (hold 10 min) and for sap: The oven temperature was programmed at an initial temperature 150 °C (hold 4 min) to 280 °C as a final temperature at an increasing rate of 5 °C/min (hold 4 min). The quantification of all the identified components was investigated using a percent relative peak area. A tentative identification of the compounds was performed based on the comparison of their relative retention time and mass spectra with those of the NIST, WILLY library data of the GC/MS system.