The components of the venom of a spiderScodra griseipes. 1. Analysis of low molecular weight products using gas chromatography/mass spectrometry

1992 ◽  
Vol 6 (4) ◽  
pp. 289-292 ◽  
Author(s):  
C. Lange ◽  
C. Paris ◽  
M.-L. Clerier
Keyword(s):  
Mass Spectrometry ◽  
Molecular Weight ◽  
Gas Chromatography ◽  
Gas Chromatography Mass Spectrometry ◽  
Low Molecular Weight ◽  
Chromatography Mass Spectrometry

scholarly journals Enzymic synthesis of indol-3-ylacetyl-myo-inositol galactoside

1982 ◽  
Vol 207 (2) ◽  
pp. 283-290 ◽  
Author(s):  
L J Corcuera ◽  
L Michalczuk ◽  
R S Bandurski
Keyword(s):  
Mass Spectrometry ◽  
Molecular Weight ◽  
Gas Chromatography ◽  
Zea Mays ◽  
Catalytic Activity ◽  
Gas Chromatography Mass Spectrometry ◽  
Low Molecular Weight ◽  
Enzymic Synthesis ◽  
Chromatography Mass Spectrometry ◽  
Ylacetic Acid

Extracts of immature kernels of Zea mays catalysed the synthesis of indol-3-ylacetyl-myo-inositol galactoside from indol-3-ylacetyl-myo-inositol and UDP-galactose. Addition of 2-mercaptoethanol was required for stability of the catalytic activity during dialysis. The enzyme could be fractionated with (NH4)2SO4, and 55% of the activity was recovered in the 30-60%-saturation fraction. The product of the reaction contained radioactivity from UDP-[U-14C]galactose and was identified as indol-3-ylacetyl-myo-inositol galactoside by gas chromatography-mass spectrometry. Therefore a UDP-galactose:indol-3-ylacetyl-myo-inositol galactosyltransferase (indol-3-ylacetyl-myo-inositol galactoside synthase) is present in developing kernels of Zea mays. The description of this enzyme, together with the enzymes described in the accompanying paper [Michalczuk & Bandurski (1982) Biochem. J. 207, 273-281] for the synthesis of indol-3-ylacetylglucose and indol-3-ylacetyl-myo-inositol, now provides mechanisms for the biosynthesis of one-half of the low-molecular-weight esters of indol-3-ylacetic acid in Zea mays.

Study of the impurities in technical-grade 1,3,5-trimethyl-1,3,5-triphenylcyclotrisiloxane by gas chromatography-mass spectrometry

2021 ◽  
Vol 87 (7) ◽  
pp. 8-16
Author(s):  
A. M. Filippov ◽  
I. Yu. Ruskol ◽  
A. R. Dolotko ◽  
E. I. Alekseeva ◽  
Р. A. Storozsenko
Keyword(s):  
Mass Spectrometry ◽  
Molecular Weight ◽  
Gas Chromatography ◽  
Linear Structure ◽  
Gas Chromatography Mass Spectrometry ◽  
Technical Grade ◽  
Main Method ◽  
Methyl Group ◽  
Chromatography Mass Spectrometry ◽  
The Impact

Polymerization of 1,3,5-trimethyl-1,3,5-triphenylcyclotrisiloxane is the main method for manufacturing methylphenylsiloxane rubbers, and copolymerization of octamethylcyclotetrasiloxane and 1,3,5-trimethyl-1,3,5-triphenylcyclotrisiloxane is the main method for production of high- and low-molecular weight dimethylmethylphenylsiloxane rubbers. The molecular weight, viscosity, and other properties of the obtained polymers depend on the purity of cyclosiloxanes. The technology of 1,3,5-trimethyl-1,3,5-triphenylcyclotrisiloxane production by thermocatalytic decomposition of methylphenylsiloxanes in the presence of lithium hydroxide or lithium silanolate, followed by vacuum rectification, makes it possible to obtain a product containing 1,3,5,7-tetramethyl-1,3,5,7-tetraphenylcyclotetrasiloxanes, tetraphenyldimethyldisiloxane as impurities and trace amounts of phenyl-containing siloxanes of cyclic and linear structure. The impurities of polycyclic and polyhedral structures have not been previously described. In this study, the method of gas chromatography-mass spectrometry is used to analyze compounds that can be present as impurities in technical-grade 1,3,5-trimethyl-1,3,5-triphenylcyclotrisiloxane. The use of the previously described regularities of the fragmentation of siloxanes of different structures made it possible to identify a number of siloxanes which are absent in the NIST 11 mass spectra library. It is shown that polycyclic and polyhedral compounds containing methylsilsesquioxane units have a short fragmentation path. They are characterized by ionization with the elimination of the methyl group and benzene in case of two phenyl groups in the molecule. The siloxane skeleton of such cations is rather stable, so they more readily lose another methyl group thus transforming into double-charged cations. The impact of electron ionization on the molecules with siloxane units containing different organic substituents at silicon leads to randomization of those substituents and rearrangement of the siloxane skeleton. Analysis of the results revealed that silanes, siloxanes of linear, cyclic, polycyclic and polyhedral structures are present in technical grade 1,3,5-trimethyl-1,3,5-triphenylcyclotrisiloxane.

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