Flame Response in the Quantitative Determination of High Molecular Weight Paraffins and Alcohols by Gas Chromatography.

1963 ◽  
Vol 35 (3) ◽  
pp. 360-362 ◽  
Author(s):  
Gerald. Perkins ◽  
R. E. Laramy ◽  
L. D. Lively
Keyword(s):  
Molecular Weight ◽  
Gas Chromatography ◽  
Quantitative Determination ◽  
High Molecular Weight ◽  
Flame Response

Determination of Peroxides in Synthetic Rubbers

1945 ◽  
Vol 18 (4) ◽  
pp. 874-876
Author(s):  
Richard F. Robey ◽  
Herbert K. Wiese
Keyword(s):  
Molecular Weight ◽  
Natural Rubber ◽  
Quantitative Determination ◽  
High Molecular Weight ◽  
Active Oxygen ◽  
Lower Molecular Weight ◽  
Synthetic Rubber ◽  
High Molecular Weight Polymers ◽  
Methanol Solutions

Abstract Peroxides are found in synthetic rubbers either as the result of attack by oxygen, usually from the air, or as a residue from polymerization operations employing peroxide catalysts. Because of possible detrimental effects of active oxygen on the properties of the rubber, a method of quantitative determination is needed. The concentration of peroxides in substances of lower molecular weight may be determined with ferrous thiocyanate reagent, either titrimetrically as recommended by Yule and Wilson or colorimetrically as by Young, Vogt, and Nieuwland. Unfortunately, many highly polymeric substances are not soluble in the acetone and methanol solutions employed in these procedures. This is also the case with hydrocarbon monomers, such as butadiene, containing appreciable concentrations of soluble high molecular weight polymers. Bolland, Sundralingam, Sutton and Tristram recommended benzene as a solvent for natural rubber samples and the reagent made up in methanol. However, most synthetic rubbers are not readily soluble even in this combination. The following procedure employs the ferrous thiocyanate reagent in combination with a solvent capable of maintaining considerable concentrations of synthetic rubber in solution. The solvent comprises essentially 20 per cent ethanol in chloroform.

scholarly journals Quantitative Determination of Low and High Molecular Weight Proteins in Human Urine: Influence of Temperature and Storage Time

1999 ◽  
Vol 45 (3) ◽  
pp. 430-432 ◽  
Author(s):  
Ina S Klasen ◽  
Louis JM Reichert ◽  
Corrie M de Kat Angelino ◽  
Jack FM Wetzels
Keyword(s):  
Molecular Weight ◽  
Quantitative Determination ◽  
High Molecular Weight ◽  
Human Urine ◽  
Storage Time ◽  
Influence Of Temperature ◽  
High Molecular Weight Proteins ◽  
And Storage

scholarly journals Determination of the δ 2H Values of High Molecular Weight Lipids by High Temperature GC Coupled to Isotope Ratio Mass Spectrometry

2020 ◽  
Author(s):  
Sabine Lengger ◽  
Yuki Weber ◽  
Kyle W. Taylor ◽  
Sebastian H. Kopf ◽  
Robert Berstan ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Molecular Weight ◽  
Gas Chromatography ◽  
High Temperature ◽  
High Molecular Weight ◽  
Isotope Ratio ◽  
Isotope Ratio Mass Spectrometry ◽  
Widespread Interest ◽  
Isotope Analyses

<div>Rationale: The hydrogen isotopic composition of lipids (δ 2Hlipid) is widely used in food</div><div>science and as a proxy for past hydrological conditions. Determining the δ 2H values of large,</div><div>well-preserved triacylglycerides and other uniquely microbial lipids, such as glycerol dialkyl</div><div>glycerol tetraether (GDGT) lipids, is thus of widespread interest but has so far not been </div><div>possible due to their size which prohibits analysis by traditional gas chromatography</div><div>pyrolysis isotope ratio mass spectrometry (GC-P-IRMS).</div><div>Methods: We determined the δ 2H values of large, polar molecules and applied high</div><div>temperature gas chromatography (GC) methods on a modified GC-P-IRMS system. The</div><div>methods were validated using authentic standards of large, functionalised molecules</div><div>(triacylglycerides, TAG), purified reference standards of GDGTs, and compared to δ 2H</div><div>values determined by elemental analyser pyrolysis isotope ratio mass spectrometry (EA-PIRMS); and subsequently applied to the analysis of GDGTs in a sample from a methane</div><div>seep and a Welsh peat.</div><div>Results: δ 2H values of TAGs agreed within error between different between GC-P-IRMS and</div><div>EA-P-IRMS, with GC-P-IRMS showing 3-5 ‰ precision for 10 ng H injected. Archaeal lipid</div><div>GDGTs with up to three cyclisations could be analysed: δ 2H values were not significantly</div><div>different between methods with standard deviations of 5 to 6 ‰. When environmental</div><div>samples were analysed, δ 38 2H values of isoGDGTs were 50 ‰ more negative than those of</div><div>terrestrial brGDGTs.</div><div>Conclusions: Our results indicate that the high temperature GC-P-IRMS (HTGC-P-IRMS)</div><div>method developed here is appropriate to determine the δ 2H values of TAGs, GDGT lipids</div><div>with up to two cyclisations, and potentially other high molecular weight compounds. The</div><div>methodology will widen the current analytical window for biomarker and alimentary light</div><div>stable isotope analyses. Moreover, our initial measurements suggest that bacterial and</div><div>archaeal GDGT δ 2H values can record environmental and ecological conditions</div>

Quantitative determination of SH groups in low- and high-molecular-weight compounds by an electron spin resonance method

1989 ◽  
Vol 182 (1) ◽  
pp. 58-63 ◽  
Author(s):  
V.V. Khramtsov ◽  
V.I. Yelinova (Popova) ◽  
L.M. Weiner ◽  
T.A. Berezina ◽  
V.V. Martin ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Electron Spin Resonance ◽  
Quantitative Determination ◽  
High Molecular Weight ◽  
Electron Spin ◽  
Resonance Method ◽  
Sh Groups ◽  
Spin Resonance ◽  
Electron Spin Resonance Method
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