scholarly journals Gas-Chromatography using ice coated fused silica-columns: Study of adsorption of sulfur dioxide on water-ice

2017 ◽  
Author(s):  
Stefan Langenberg ◽  
Ulrich Schurath
Keyword(s):  
Gas Chromatography ◽  
Sulfur Dioxide ◽  
Vertical Displacement ◽  
Fused Silica ◽  
Experimental Conditions ◽  
Water Ice ◽  
Temperature Range ◽  
Reaction With Water ◽  
The Impact ◽  
Peak Retention Time

Abstract. The well-established technique of gas chromatography is used to investigate interactions of sulfur dioxide with a crystalline ice film in a fused silica wide-bore column. Peak shape analysis of SO2 chromatograms measured in the temperature range 205–265 K is applied to extract parameters describing a combination of three processes: (i) physisorption of SO2 at the surface; (ii) dissociative reaction with water; (iii) slow uptake into bulk ice. Process (ii) is described by a dissociative Langmuir isotherm. The pertinent monolayer saturation capacity is found to increase with temperature. The impact of process (iii) on SO2 peak retention time is found to be negligible under our experimental conditions. By analyzing binary chromatograms of hydrophobic n-hexane and hydrophilic acetone, the premelt surface layer is probed in the temperature range 221–263 K possibly giving rise to irregular adsorption. Both temperature dependencies fit simple van't Hoff equations as expected for process (i), implying that irregular adsorption of acetone is negligible in the probed temperature range. Adsorption enthalpies of −45 ± 5 kJ mol−1 and −23 ± 2 kJ mol−1 are obtained for acetone and n-hexane. Our study was motivated to assess the vertical displacement of SO2 and acetone in the wake of aircraft by adsorption on ice particles and their subsequent sedimentation. Our results suggest that this transport mechanism is negligible.

scholarly journals Gas chromatography using ice-coated fused silica columns: study of adsorption of sulfur dioxide on water ice

2018 ◽  
Vol 18 (10) ◽  
pp. 7527-7537 ◽  
Author(s):  
Stefan Langenberg ◽  
Ulrich Schurath
Keyword(s):  
Gas Chromatography ◽  
Sulfur Dioxide ◽  
Vertical Displacement ◽  
Fused Silica ◽  
Water Ice ◽  
Temperature Range ◽  
Reaction With Water ◽  
The Impact ◽  
Peak Retention Time ◽  
Established Technique

Abstract. The well established technique of gas chromatography is used to investigate interactions of sulfur dioxide with a crystalline ice film in a fused silica wide bore column. Peak shape analysis of SO2 chromatograms measured in the temperature range 205–265 K is applied to extract parameters describing a combination of three processes: (i) physisorption of SO2 at the surface, (ii) dissociative reaction with water and (iii) slow uptake into bulk ice. Process (ii) is described by a dissociative Langmuir isotherm. The pertinent monolayer saturation capacity is found to increase with temperature. The impact of process (iii) on SO2 peak retention time is found to be negligible under our experimental conditions.By analyzing binary chromatograms of hydrophobic n-hexane and hydrophilic acetone, the premelt surface layer is investigated in the temperature range 221–263 K, possibly giving rise to irregular adsorption. Both temperature dependencies fit simple van't Hoff equations as expected for process (i), implying that irregular adsorption of acetone is negligible in the investigated temperature range. Adsorption enthalpies of −45 ± 5 and −23±2 kJ mol−1 are obtained for acetone and n-hexane.The motivation of our study was to assess the vertical displacement of SO2 and acetone in the wake of aircraft by adsorption on ice particles and their subsequent sedimentation. Our results suggest that this transport mechanism is negligible.

scholarly journals Light-Struck Taste in White Wine: Protective Role of Glutathione, Sulfur Dioxide and Hydrolysable Tannins

Molecules ◽  
2021 ◽  
Vol 26 (17) ◽  
pp. 5297
Author(s):  
Daniela Fracassetti ◽  
Sara Limbo ◽  
Natalia Messina ◽  
Luisa Pellegrino ◽  
Antonio Tirelli
Keyword(s):  
Sulfur Dioxide ◽  
Light Exposure ◽  
Dimethyl Disulfide ◽  
White Wine ◽  
Protective Role ◽  
Experimental Conditions ◽  
White Wines ◽  
Hydrolysable Tannins ◽  
The Impact

Light exposure of white wine can cause a light-struck taste (LST), a fault induced by riboflavin (RF) and methionine (Met) leading to the formation of volatile sulfur compounds (VSCs), including methanethiol (MeSH) and dimethyl disulfide (DMDS). The study aimed to investigate the impact of different antioxidants, i.e., sulfur dioxide (SO2), glutathione (GSH) and chestnut tannins (CT), on preventing LST in model wine (MW) and white wine (WW), both containing RF and Met. Both MW and WW samples were added with the antioxidants, either individually or in different combinations, prior to 2-h light exposure and they were stored in the dark for 24 months. As expected, the light induced the degradation of RF in all the conditions assayed. Met also decreased depending on the antioxidants added. The presence of antioxidants limited the formation of LST as lower concentrations of VSCs were found in both MW and WW samples. In the latter matrix, neither MeSH nor DMDS were detected in the presence of CT, while only DMDS was found in WW+GSH, WW+SO2+GSH and WW+CT+SO2 samples at a concentration lower than the perception thresholds. Considering the antioxidants individually, the order of their effectiveness was CT ≥ GSH > SO2 in WW under the adopted experimental conditions. The results indicate tannins as an effective enological tool for preventing LST in white wine and their use will be further investigated in different white wines under industrial scale.

Adsorption of organics on thermally treated solids obtained from colloidal silica

1987 ◽  
Vol 52 (3) ◽  
pp. 572-581 ◽  
Author(s):  
Miroslav M. Kopečni ◽  
Slobodan K. Milonjic ◽  
Wladyslaw Rudzinski ◽  
Jacek Jagiello
Keyword(s):  
Gas Chromatography ◽  
Thermodynamic Parameters ◽  
Adsorption Isotherms ◽  
Colloidal Silica ◽  
Adsorption Properties ◽  
Thermal Pretreatment ◽  
Lateral Interactions ◽  
Adsorbed Molecules ◽  
Temperature Range ◽  
Thermally Treated

Adsorption isotherms of three adsorbates on the solid beads obtained from colloidal silica were determined by means of gas chromatography at low surface coverages, when lateral interactions between the adsorbed molecules are negligible. The influence of thermal pretreatment on the adsorption properties of the solids was investigated in the temperature range from 343 to 423 K, while the solids were heated between 523 K and 1 223 K. The thermodynamic parameters of adsorption have been determined and used to discuss the adsorbate-adsorbent interactions.

scholarly journals Glucuronides Hydrolysis by Intestinal Microbial β-Glucuronidases (GUS) Is Affected by Sampling, Enzyme Preparation, Buffer pH, and Species

Pharmaceutics ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1043
Author(s):  
Christabel Ebuzoeme ◽  
Imoh Etim ◽  
Autumn Ikimi ◽  
Jamie Song ◽  
Ting Du ◽  
...  
Keyword(s):  
Enzyme Preparation ◽  
Reaction System ◽  
Reaction Rates ◽  
Experimental Conditions ◽  
Model Animal ◽  
Fresh Feces ◽  
Time Buffer ◽  
Exogenous Compounds ◽  
Activity Loss ◽  
The Impact

Glucuronides hydrolysis by intestinal microbial β-Glucuronidases (GUS) is an important procedure for many endogenous and exogenous compounds. The purpose of this study is to determine the impact of experimental conditions on glucuronide hydrolysis by intestinal microbial GUS. Standard probe 4-Nitrophenyl β-D-glucopyranoside (pNPG) and a natural glucuronide wogonoside were used as the model compounds. Feces collection time, buffer conditions, interindividual, and species variations were evaluated by incubating the substrates with enzymes. The relative reaction activity of pNPG, reaction rates, and reaction kinetics for wogonoside were calculated. Fresh feces showed the highest hydrolysis activities. Sonication increased total protein yield during enzyme preparation. The pH of the reaction system increased the activity in 0.69–1.32-fold, 2.9–12.9-fold, and 0.28–1.56-fold for mouse, rat, and human at three different concentrations of wogonoside, respectively. The Vmax for wogonoside hydrolysis was 2.37 ± 0.06, 4.48 ± 0.11, and 5.17 ± 0.16 μmol/min/mg and Km was 6.51 ± 0.71, 3.04 ± 0.34, and 0.34 ± 0.047 μM for mouse, rat, and human, respectively. The inter-individual difference was significant (4–6-fold) using inbred rats as the model animal. Fresh feces should be used to avoid activity loss and sonication should be utilized in enzyme preparation to increase hydrolysis activity. The buffer pH should be appropriate according to the species. Inter-individual and species variations were significant.

Determination of multi pesticide residues in leaf and needle samples using a modified QuEChERS approach and gas chromatography-tandem mass spectrometry

2021 ◽  
Author(s):  
Arnelle Löbbert ◽  
Sonja Schanzer ◽  
Henrik Krehenwinkel ◽  
Franz Bracher ◽  
Christoph Müller
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Tandem Mass Spectrometry ◽  
Forest Ecosystems ◽  
Tandem Mass ◽  
Modified Quechers ◽  
Chromatography Tandem Mass Spectrometry ◽  
The Impact ◽  
Impact Of Pesticides

A novel, validated QuEChERS-based GC-MS/MS method was developed, which will allow the assessment of the impact of pesticides on forest ecosystems.

scholarly journals Reservoir-Induced Land Deformation: Case Study from the Grand Ethiopian Renaissance Dam

2021 ◽  
Vol 13 (5) ◽  
pp. 874
Author(s):  
Yu Chen ◽  
Mohamed Ahmed ◽  
Natthachet Tangdamrongsub ◽  
Dorina Murgulet
Keyword(s):  
Land Surface ◽  
Large Scale ◽  
Surface Deformation ◽  
Vertical Displacement ◽  
Nile River ◽  
Reservoir Volume ◽  
Novel Approach ◽  
Land Deformation ◽  
Large Scale Land ◽  
The Impact

The Nile River stretches from south to north throughout the Nile River Basin (NRB) in Northeast Africa. Ethiopia, where the Blue Nile originates, has begun the construction of the Grand Ethiopian Renaissance Dam (GERD), which will be used to generate electricity. However, the impact of the GERD on land deformation caused by significant water relocation has not been rigorously considered in the scientific research. In this study, we develop a novel approach for predicting large-scale land deformation induced by the construction of the GERD reservoir. We also investigate the limitations of using the Gravity Recovery and Climate Experiment Follow On (GRACE-FO) mission to detect GERD-induced land deformation. We simulated three land deformation scenarios related to filling the expected reservoir volume, 70 km3, using 5-, 10-, and 15-year filling scenarios. The results indicated: (i) trends in downward vertical displacement estimated at −17.79 ± 0.02, −8.90 ± 0.09, and −5.94 ± 0.05 mm/year, for the 5-, 10-, and 15-year filling scenarios, respectively; (ii) the western (eastern) parts of the GERD reservoir are estimated to move toward the reservoir’s center by +0.98 ± 0.01 (−0.98 ± 0.01), +0.48 ± 0.00 (−0.48 ± 0.00), and +0.33 ± 0.00 (−0.33 ± 0.00) mm/year, under the 5-, 10- and 15-year filling strategies, respectively; (iii) the northern part of the GERD reservoir is moving southward by +1.28 ± 0.02, +0.64 ± 0.01, and +0.43 ± 0.00 mm/year, while the southern part is moving northward by −3.75 ± 0.04, −1.87 ± 0.02, and −1.25 ± 0.01 mm/year, during the three examined scenarios, respectively; and (iv) the GRACE-FO mission can only detect 15% of the large-scale land deformation produced by the GERD reservoir. Methods and results demonstrated in this study provide insights into possible impacts of reservoir impoundment on land surface deformation, which can be adopted into the GERD project or similar future dam construction plans.

scholarly journals A flexible ChIP-sequencing simulation toolkit

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
An Zheng ◽  
Michael Lamkin ◽  
Yutong Qiu ◽  
Kevin Ren ◽  
Alon Goren ◽  
...  
Keyword(s):  
Ground Truth ◽  
Peak Calling ◽  
Simulation Framework ◽  
Experimental Conditions ◽  
Ground Truth Data ◽  
Chip Sequencing ◽  
Genome Wide ◽  
Experimental Parameters ◽  
Differential Binding ◽  
The Impact

Abstract Background A major challenge in evaluating quantitative ChIP-seq analyses, such as peak calling and differential binding, is a lack of reliable ground truth data. Accurate simulation of ChIP-seq data can mitigate this challenge, but existing frameworks are either too cumbersome to apply genome-wide or unable to model a number of important experimental conditions in ChIP-seq. Results We present ChIPs, a toolkit for rapidly simulating ChIP-seq data using statistical models of key experimental steps. We demonstrate how ChIPs can be used for a range of applications, including benchmarking analysis tools and evaluating the impact of various experimental parameters. ChIPs is implemented as a standalone command-line program written in C++ and is available from https://github.com/gymreklab/chips. Conclusions ChIPs is an efficient ChIP-seq simulation framework that generates realistic datasets over a flexible range of experimental conditions. It can serve as an important component in various ChIP-seq analyses where ground truth data are needed.

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