Enantiomer Separation by Capillary SFC and GC on Chirasil-Nickel: Observation of Unusual Peak Broadening Phenomena

1994 ◽  
Vol 66 (18) ◽  
pp. 2893-2897 ◽  
Author(s):  
Michael. Schleimer ◽  
Markus. Fluck ◽  
Volker. Schurig
Keyword(s):  
Enantiomer Separation ◽  
Peak Broadening ◽  
Capillary Sfc

Enantiomer separation by capillary SFC and GC on immobilized permethyl-β-cyclodextrin: A systematic comparison

1992 ◽  
Vol 4 (1) ◽  
pp. 23-28 ◽  
Author(s):  
Dieter Schmalzing ◽  
Graeme J. Nicholson ◽  
Martin Jung ◽  
Volker Schurig
Keyword(s):  
Enantiomer Separation ◽  
Systematic Comparison ◽  
Capillary Sfc

Enantiomer separation by capillary SFC and GC on immobilized octakis(2,6-di-O-methyl-3-O-pentyl)-γ-cyclodextrin

1994 ◽  
Vol 17 (11) ◽  
pp. 779-783 ◽  
Author(s):  
Jürgen Dönnecke ◽  
Wilfried A. König ◽  
Olle Gyllenhaal ◽  
Jörgen Vessman ◽  
Christian Schulze
Keyword(s):  
Enantiomer Separation ◽  
Capillary Sfc

scholarly journals Reducing the Crystallite Size of Spherulites in PEO-Based Polymer Nanocomposites Mediated by Carbon Nanodots and Ag Nanoparticles

Nanomaterials ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 874 ◽  
Author(s):  
Ranjdar Abdullah ◽  
Shujahadeen Aziz ◽  
Soran Mamand ◽  
Aso Hassan ◽  
Sarkawt Hussein ◽  
...  
Keyword(s):  
Crystallite Size ◽  
Polymer Nanocomposites ◽  
Electron Transition ◽  
Peak Position ◽  
Carbon Nanodots ◽  
Ag Nps ◽  
Peak Broadening ◽  
Vis Spectroscopy ◽  
Solution Cast ◽  
Significant Change

The PEO-based polymer nanocomposites were prepared by solution cast method. Green approaches were used for synthesis of carbon nanodots (CNDs) and silver nanoparticles (Ag NPs). It was found that the crystallite size of spherulites of PEO was greatly scarified upon incorporation of CNDs and Ag NPs. In the present work, in opposition to other studies, broadening of surface plasmon resonance (SPR) peak of metallic Ag NPs in PEO-based polymer composites was observed rather than peak tuning. Various techniques, such as powder X-ray diffraction (XRD), SEM, UV–Vis spectroscopy, and photoluminescence (PL), were used to characterize the structural, morphological, and optical properties of the samples. Increase of amorphous phase for the PEO doped with CND particles was shown from the results of XRD analyses. Upon the addition of suspended Ag NPs to the PEO:CNDs composites, significant change of XRD peak position was seen. A field-emission scanning electron microscope (FESEM) was used to investigate the surface morphology of the samples. In the SEM, a significant change in the crystalline structure was seen. The size of PEO spherulites in the PEO nanocomposite samples became smaller and the percentage of amorphous portion became larger, owing to the distribution of CNDs and Ag NPs. The UV–Vis absorption spectra of the PEO-based polymer were found to improve and shift to higher wavelengths upon incorporation of CNDs and Ag NPs into the PEO matrix. The SPR peak broadening in the UV–Vis spectra was observed in the PEO:CNDs composites due to the Ag NPs. The absorption edge value of PEO was found to shift toward lower photon energy as the CNDs and Ag NPs are introduced. The photoluminescence (PL) spectra were also observed for the PEO:CNDs and PEO:CNDs:Ag samples and found to be more intense in the PEO:CNDs system than in the PEO:CNDs:Ag system. Lastly, the optical band gap of the samples was further studied in detail using of Tauc’s model and optical dielectric loss parameter. The types of electron transition were specified.

SAMPLE INJECTION IN PROGRAMMED TEMPERATURE GAS CHROMATOGRAPHY AND ITS SIGNIFICANCE FOR TRACE ANALYSIS

1965 ◽  
Vol 43 (5) ◽  
pp. 1560-1568 ◽  
Author(s):  
L. W. Hollingshead ◽  
H. W. Habgood ◽  
W. E. Harris
Keyword(s):  
Trace Analysis ◽  
Initial Temperature ◽  
Retention Volume ◽  
Total Sample ◽  
Sample Volume ◽  
Plate Height ◽  
Peak Broadening ◽  
Increased Sensitivity ◽  
Experimental Values ◽  
Total Sample Volume

The measurement of apparent plate heights resulting from various values of the total sample volume has been carried out for C5 to C8n-alkanes on Apiezon L under both isothermal and p.t.g.c. conditions. Plug injection of samples was achieved through the use of a syringe plunger driven at constant speed by a motor. The time for injection of gas samples ranged from 1 to 300 s. All of the results, both isothermal and p.t.g.c, could be correlated to the same plot of Happ/Hc against √nΔVs/VT0 where Happ is the observed plate height, Hc the limiting plate height at low sample volumes, n the true plate number, ΔVs the sample volume, and VT0 the isothermal retention volume at the initial temperature. The experimental values lie somewhat above the theoretical curve calculated by van Deemter et al. It is confirmed that sample volumes less than [Formula: see text] give negligible excess peak broadening. Applying these concepts to trace analysis, very large samples may be used in p.t.g.c. under such initial temperature conditions that the major component is only weakly retained, while traces of heavier components are concentrated into narrow bands and eluted as sharp peaks with the increased sensitivity provided by the large sample. As an example, chromatograms are presented for the p.t.g.c. analysis of natural gas on deactivated alumina, using sample volumes ranging from 2 to 500 ml.

scholarly journals Low temperature synthesis and characterization of Mn3O4 nanoparticles

2007 ◽  
Vol 5 (1) ◽  
pp. 169-176 ◽  
Author(s):  
Abdülhadi Baykal ◽  
Yüksel Köseoğlu ◽  
Mehmet Şenel
Keyword(s):  
Particle Size ◽  
Infrared Spectroscopy ◽  
Low Temperature ◽  
Synthesis And Characterization ◽  
Low Temperature Synthesis ◽  
Temperature Synthesis ◽  
X Ray ◽  
Peak Broadening ◽  
Mn3o4 Nanoparticles

AbstractHeating hydrous manganese (II) hydroxide gel at 85 °C for 12 hours produces Mn3O4 nanoparticles. They were characterized by X-ray powder diffraction (XRD) and infrared spectroscopy (FTIR). The particle size estimated from the SEM and X-ray peak broadening is approximately 32 nm, showing them to be nanocrystalline. EPR measurements confirm a typical Mn2+signal with a highly resolved hyperfine structure.

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