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Gas Chromatographic Analysis
Published in Adorjan Aszalos, Modern Analysis of Antibiotics, 2020
Brown [13] reported on the analyses of formulations of this fungicide. The flask-heater-injection port and column (1% QF-1 on Gas Chrom Q 80/100) were both at 200°C and the FID at 225°C. The internal standard was cholesteryl acetate and silylating agent was a combination of TMCS and BSTFA. Initially, two peaks of derivatized cycloheximide were observed, the mono- and disubstituted derivatives. By adding isopropanol, quantitative yields of only the monosubstitution derivative were obtained. Mass spectrometry was used to identify the observed peaks.
Production, Extraction and Characterization of Alginates from Seaweeds
Published in Gokare A. Ravishankar, Ranga Rao Ambati, Handbook of Algal Technologies and Phytochemicals, 2019
Faiez Hentati, Alina V. Ursu, Guillaume Pierre, Cedric Delattre, Bogdan Trica, Slim Abdelkafi, Gholamreza Djelveh, Tanase Dobre, Philippe Michaud
Gaz Chromatography coupled with Mass Spectrometry and Electron Ionization (GC/MS-EI) is another method for determining M/G ratios of hydrolyzed alginates (trifluoroacetic acid 2 M, 90 min, 120°C) after derivatization of their constitutive uronic acids (Hentati et al. 2018). Silylation using BSTFA (Bis (trimethysilyl) trifluoroacetamide) and TMCS (trimethylchlorosilane) reagents (99:1–90:10) is the most common method used at various temperatures (from ambient temperature to 80°C) and reactions times (30 to 240 min). Trimethylsilyl-O-glycosides into dichloromethane can be separated for example into a OPTIMA-1MS column eluted with a helium flow rate (Hentati et al. 2018).
Glycerine Analysis
Published in Eric Jungermann, Norman O.V. Sonntag, Glycerine, 2018
A report by Molever [32] illustrates these trends for the analysis of glycerine in soap. Samples are prepared by blending about 10 g of soap with 200 ml of N.N-dimethyl formamide. After filtration to remove insoluble soap, a portion of the solution is reacted with BSTFA (bis-trimethylsilyltrifuroacetamide) to produce the silylated glycerine derivative. The column used is a 12 m × 0.2 mm i.d. fused silica capillary coated with methyl silicone fluid. Glycerol was analyzed isothermally at 100°C. Quantitation was dne by comparing peak areas of the sample with peak areas of external standards.
Steroid hormone levels in postmenopausal hysterectomised women with and without ovarian conservation: the continuous endocrine function of the ovaries
Published in Journal of Obstetrics and Gynaecology, 2023
Elsa Nunes, Eugenia Gallardo, Sara Morgado-Nunes, José Fonseca-Moutinho
Plasma samples were stored at −80°C and protected from light until analysis. The studied compounds, dehydroepiandrosterone (DHEA), androstenedione (A), 17β-oestradiol (E2) and testosterone (T) were quantified by solid phase extraction (SPE) and gas chromatography and tandem mass spectrometry (GC-MS/MS). Briefly, 1 mL of plasma was diluted with 1 mL of phosphate buffer saline (PBS) (pH = 7) and spiked with 100 µL of internal standard (DHEA-d6). SPE cartridges (Oasis® HLB 3 cc, Waters, USA) were conditioned with 2 mL of methanol and 2 mL of 0.1% acetic acid. After passing of the sample through the cartridge, this was washed with 2 mL of deionised water. The columns were afterwards dried under full vacuum for 30 min and the analytes were eluted with 2 mL methanol. The extracts were concentrated to dryness under a gentle nitrogen stream, and were afterwards dissolved in 20 μL of methanol, from which a 3 μL aliquot was injected into the GC-MS/MS system. The remaining residue was further evaporated to dryness under a gentle nitrogen stream at 36 °C, and 20 μL of N,O-Bis(trimethylsilyl)trifluoroacetamide (BSTFA) was added. Derivatization took place in a domestic digital microwave oven (Candy CMG 2017 M, Portugal) for 2 min at 800 W, and 3 μL was injected. This step was deemed necessary because some of the analytes under study (E2 and T) present active moieties and need to be derivatized before analysis by GC-based procedures.
Enhanced full-thickness wound healing via Sophora gibbosa extract delivery based on a chitosan/gelatin dressing incorporating microemulsion
Published in Drug Development and Industrial Pharmacy, 2021
Khaled Shalaby, Ehab M. Mostafa, Arafa Musa, Abd El Ghany A. Moustafa, Mohamed F. Ibrahim, Nabil K. Alruwaili, Ameeduzzafar Zafar, Mohammed Elmowafy
Pluronic F127 was purchased from Sigma Aldrich (Germany). Sorbitane monooleate (Span 80), polysorbate 80 (Tween 80), polyethylene glycol 400 (PEG 400) and polyethylene glycol 1500 (PEG 1500) were purchased from Lobal Chemie (India). Transcutol HP was kindly gifted by Gattefose (France). Chitosan (molecular weight: 100,000-300,000; degree of deacetylation: 85%) was purchased from ACROS organics (USA). Gelatin (molecular weight: 20 kDa) and glycerol were purchased from MERK (Germany). The aerial parts of Sophora gibbosa were collected in April 2018 from the desert of Aljouf region, in the north of the Kingdom of Saudi Arabia (KSA). It was identified by Mr. Hamdan Ogereef Al-Hassan, M.Sc. (Camel and Range Research Center), Aljouf, KSA. A voucher specimen was kept and deposited at the herbarium of the Pharmacognosy Department, College of Pharmacy, Jouf University. Trimethylchlorosilane (TMCS) and N,O-bis-trimethylsilyltrifluroacetamide (BSTFA) were purchased from Sigma-Aldrich (St. Louis, MO, USA). All the other chemicals, reagents and solvents used were of analytical reagent grade.
Lipidomic analysis of cancer cells cultivated at acidic pH reveals phospholipid fatty acids remodelling associated with transcriptional reprogramming
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2020
Lorena Urbanelli, Sandra Buratta, Mariantonia Logozzi, Nico Mitro, Krizia Sagini, Rossella Di Raimo, Donatella Caruso, Stefano Fais, Carla Emiliani
Total cholesterol quantitative analysis was performed as previously described41. Briefly, an aliquot of fraction B was first derivatized with a mixture of bis-trimethylsilyltrifluoroacetamide (BSTFA): pyridine (4:1 v/v) for 30 min at 60 °C, and then injected into a gas chromatograph-mass spectrometer (GC-MS, Varian Saturn 2100). The MS was operated in the electron impact (EI) ionisation mode. GC-MS analysis was performed as follows: 1 μl sample was injected in splitless mode (inlet was kept at 270 °C with the helium flow at 1.0 ml/min) at the initial 180 °C. The oven was first kept at 180 °C for 1 min, ramped at 50 °C/min to 240 °C, then at 5 °C/min to 300 °C for 6 min. The ions used for the quantification of cholesterol were at m/z 368 for cholesterol and m/z 357 for 5α-cholestane, the IS. The selection of ions for selective ion monitoring (SIM) analysis was based on mass spectra of pure standards and the quantification was based on calibration curves freshly prepared using a fixed concentration of the IS, and different concentrations of cholesterol, in a range from 0 to 10 μg/μl. Quantitative data were normalised on the protein content of cells.