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In Vivo Assessment of Dermal Absorption
Published in David W. Hobson, Dermal and Ocular Toxicology, 2020
George J. Klain, William G. Reifenrath
The meaningful use of nonradioactive test compounds in in vivo dermal penetration studies depends on the sensitivity of analytical techniques to measure the concentration in blood and urine. Blood levels after topical application are usually very low due to dilution, tissue uptake, or rapid excretion. It may be difficult to completely extract the test compound from tissues. Appropriate analytical techniques include high performance liquid chromatography, gas-liquid chromatography with various detectors, bioassays, enzyme immunoassays, spectrophotometric, and spectrofluorometric methods. These are techniques of general acceptability and their use will depend on the design of each study.
Current Perspectives and Methods for the Characterization of Natural Medicines
Published in Rohit Dutt, Anil K. Sharma, Raj K. Keservani, Vandana Garg, Promising Drug Molecules of Natural Origin, 2020
Muthusamy Ramesh, Arunachalam Muthuraman, Nallapilai Paramakrishnan, Balasubramanyam I. Vishwanathan
Chromatography is a major method for the separation of bioactive products from natural resources. This technique works based on the distribution of molecules in different phases. The natural compounds are distributed into two different phases, i.e. stationary phase and mobile phase. Based on the relative distribution of the chemical constituents, the constituents are separated. Chromatography is functioning by different methods: (i) column/adsorption chromatography; (ii) partition chromatography; (iii) paper chromatography; (iv) thin-layer chromatography; (v) gas-liquid chromatography; (vi) gas-solid chromatography; and (vii) ion-exchange chromatography. The parameters such as retention factor, selectivity, efficiency, retention time, and peak area are investigated for the structural characterization of marine products based on chromatography. Different types of chromatography techniques employed in the isolation and characterization of phytochemicals and marine constituents are tabulated in Table 2.1.
Gas Chromatographic Analysis
Published in Adorjan Aszalos, Modern Analysis of Antibiotics, 2020
Gas chromatography, by definition, includes those separations that involve gas as the mobile phase. Two primary categories are gas-solid chromatography and gas-liquid chromatography (GLC), which involve solids or liquids, respectively, as stationary phases packed in columns. In the former case, the analyte is adsorbed by the solid, and in the latter the analyte dissolves in the stationary liquid. The volatility of the analyte effects partitioning as more gas is passed along the column. The preponderance of GC methods involving antibiotics are by GLC.
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.
RNA-sequencing revealed apple pomace ameliorates expression of genes in the hypothalamus associated with neurodegeneration in female rats fed a Western diet during adolescence to adulthood
Published in Nutritional Neuroscience, 2023
Ayad A. Alawadi, Vagner A. Benedito, R. Chris Skinner, Derek C. Warren, Casey Showman, Janet C. Tou
Lipid analysis was previously described. Briefly, extraction of lipids from diet and brain tissue were performed using 2:1 chloroform:methanol. Total lipid content of the brain was determined gravimetrically. Extracted lipids were transmethylated into fatty acid methyl esters (FAMEs) with 50 µL of nonadecanoic acid (19:0) added as an internal standard. FAMEs were analyzed using gas–liquid chromatography (GLC) (model CP-3800; Varian, Walnut Creek, CA, USA). Fatty acids were identified by retention time and quantified using peak counts using Quantitative 37 Component FAMEs Sigma Mix (Supelco, Bellefonte, PA, USA) as the standard. All samples were performed in duplicate and reported as % of total fatty acids [10].
Change of plasmalogen content of red blood cells in myocardial hypoxia and acidosis
Published in Acta Cardiologica, 2018
Alexander Nikolaevich Osipenko
For this purpose, the method of gas–liquid chromatography was employed [16], with the registration of chemical compounds determined with flame ionisation detectors (Figure 1). The measurements were carried out by gas chromatographs GC-1000 Chromos and Tsvet-800 (Dzerzhinsk, Russia).