Identification of trans-diene isomers in hydrogenated soybean oil by gas chromatography, silver nitrate thin-layer chromatography, and carbon-13 NMR spectroscopy

1989 ◽  
Vol 37 (3) ◽  
pp. 637-642 ◽  
Author(s):  
Richard E. McDonald ◽  
David J. Armstrong ◽  
George P. Kreishman
2015 ◽  
Vol 72 (4) ◽  
pp. 248-252 ◽  
Author(s):  
Sri A. Febriana ◽  
Erik Zimerson ◽  
Cecilia Svedman ◽  
Winarto Haryadi ◽  
Pieter-Jan Coenraads ◽  
...  

2021 ◽  
Vol 83 (6) ◽  
pp. 49-54
Author(s):  
B.P. Matselyukh ◽  

The aim of this work was the isolation, purification and some properties investigation of two regulators of antibiotic biosynthesis of streptomycetes. Methods includes extraction of regulators from agar cultures and their concentration by vacuum rotary evaporator, thin layer chromatography and spectrophotometry. Results. Two strains of streptomycetes AN26 and B35 isolated from soils of different regions of Ukraine produce the regulators restoring the landomycin E biosynthesis and sporulation in mutant strain Streptomyces globispoprus 1912-B2. Both regulators were purified by thin layer chromatography and have the same Rf 0.69. Absorption curves of regulators were established by means of spectrophotometry. Maxima of absorption of regulators were 232.5 nm. The next study of the isolated regulators by means of NMR will give the possibility to elucidate their molecular structures. Conclusions. It is shown that two strains of streptomycetes isolated from the soils of Askania Nova and Brovary produce transcriptional regulators such as signaling molecules, which, like A-factor, restore the biosynthesis of antibiotics landomycin E and streptomycin in test strains S. globisporus 1912-B2 and S. griseis 1439, respectively. In terms of absorption maxima, they are similar and differ from similar indicators of known regulators of streptomycetes. It is possible that these compounds belong to new, not yet described signaling molecules, and the answer to this question will give future studies of their molecular structure by NMR spectroscopy.


2017 ◽  
Vol 54 (3) ◽  
pp. 294
Author(s):  
Hari Ramakrishnan K. ◽  
Janaky Ranjithkumar

Vitamin E, the fat soluble vitamin is present naturally in some foods and added in food supplements, nutraceuticals etc due to its vital biological function as an antioxidant. Various methods are available for the analysis of vitamin E. Especially High Performance Liquid Chromatography (HPLC) and Gas Chromatography (GC) are exclusively used for the quantitative evaluation of vitamin E, which has also identified the four different isomeric forms of this vitamin. The rate of losses of this vitamin during food processing and analysis, in addition to their transient dynamics, presents complexities in developing a highly sensitive procedure for their separations. Though effective, HPLC instrument is expensive and comparatively cumbersome. In this prospective, the study was to evaluate the usefulness of High Performance Thin Layer Chromatography (HPTLC) in the analysis of vitamin E. There are methods available using Thin Layer Chromatography for its analysis, but they are not sensitive enough to identify the isomeric forms of vitamin E. In this HPTLC method, the different isomeric forms of vitamin E - α, β, γ and δ were identified. This technique shall be considered as an alternative to the other methods such as HPLC and GC.


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