Ammonia RF−Plasma on PTFE Surfaces: Chemical Characterization of the Species Created on the Surface by Vapor−Phase Chemical Derivatization

2001 ◽  
Vol 105 (50) ◽  
pp. 12490-12497 ◽  
Author(s):  
P. Chevallier ◽  
M. Castonguay ◽  
S. Turgeon ◽  
N. Dubrulle ◽  
D. Mantovani ◽  
...  
Keyword(s):  
Vapor Phase ◽  
Chemical Characterization ◽  
Rf Plasma ◽  
Chemical Derivatization ◽  
Phase Chemical

Ammonia RF-Plasma on PTFE Surfaces: Quantification of the Species Created on the Surface by Vapor - Phase Chemical Derivatization

2000 ◽  
Vol 662 ◽  
Author(s):  
Chevallier P. ◽  
Castonguay M. ◽  
Mantovani D. ◽  
Laroche G.
Keyword(s):  
Plasma Treatment ◽  
Vapor Phase ◽  
Photoelectron Spectroscopy ◽  
Polymer Surface ◽  
Chemical Species ◽  
Direct Determination ◽  
Internal Surface ◽  
Rf Plasma ◽  
Chemical Derivatization ◽  
Phase Chemical

AbstractA cylindrically-configured plasma treatment system in Radio Frequency Glow Discharges fed with ammonia was used with the aim of modifying the internal surface of ePTFE arterial prostheses to improve their biocompatibility. In order to understand the effects of this treatment on the PTFE polymer surface, we have first realized RF-plasma treatment experiments on PTFE films. Preliminary XPS analyses have shown that about 15% of the surface atoms were substituted by nitrogen (N/C ratio of 0.3) whereas the F/C ratio decreased from 2 to 0.6, therefore leading to the conclusion that several chemical species are created onto the surface upon an ammonia plasma treatment. As X-Ray Photoelectron Spectroscopy (XPS) analysis does not allow the direct determination of the nature of the N-species grafted on the surface (chemical shifts are not different enough), vapor phase chemical derivatization was carried out on PTFE films to quantify the concentration of these new surface moities grafted on the polymer surface.

scholarly journals LC–HRMS and Chemical Derivatization Strategies for the Structure Elucidation of Caribbean Ciguatoxins: Identification of C-CTX-3 and -4

Marine Drugs ◽  
2020 ◽  
Vol 18 (4) ◽  
pp. 182 ◽  
Author(s):  
Fedor Kryuchkov ◽  
Alison Robertson ◽  
Christopher O. Miles ◽  
Elizabeth M. Mudge ◽  
Silvio Uhlig
Keyword(s):  
Chemical Characterization ◽  
Diagnostic Value ◽  
Chemical Derivatization ◽  
Oxidation Reactions ◽  
Structural Modifications ◽  
Low Concentrations ◽  
Simple Chemical ◽  
Product Ions ◽  
Mass Spectrometric Fragmentation

Ciguatera poisoning is linked to the ingestion of seafood that is contaminated with ciguatoxins (CTXs). The structural variability of these polyether toxins in nature remains poorly understood due to the low concentrations present even in highly toxic fish, which makes isolation and chemical characterization difficult. We studied the mass spectrometric fragmentation of Caribbean CTXs, i.e., the epimers C-CTX-1 and -2 (1 and 2), using a sensitive UHPLC–HRMS/MS approach in order to identify product ions of diagnostic value. We found that the fragmentation of the ladder-frame backbone follows a characteristic pattern and propose a generalized nomenclature for the ions formed. These data were applied to the structural characterization of a pair of so far poorly characterized isomers, C-CTX-3 and -4 (3 and 4), which we found to be reduced at C-56 relative to 1 and 2. Furthermore, we tested and applied reduction and oxidation reactions, monitored by LC–HRMS, in order to confirm the structures of 3 and 4. Reduction of 1 and 2 with NaBH4 afforded 3 and 4, thereby unambiguously confirming the identities of 3 and 4. In summary, this work provides a foundation for mass spectrometry-based characterization of new C-CTXs, including a suite of simple chemical reactions to assist the examination of structural modifications.

Olfactory and Chemical Characterization of Indoor Air-Towards a Psychophysical Model for Air Quality

1981 ◽  
Author(s):  
Birgitta Berglund ◽  
Ulf Berglund ◽  
Thomas Lindvall ◽  
Helene Nicander-Bredberg
Keyword(s):  
Air Quality ◽  
Indoor Air ◽  
Chemical Characterization

PURIFICATION AND PARTIAL CHEMICAL CHARACTERIZATION OF SHEEP NEUROPHYSIN

1973 ◽  
Vol 74 (2) ◽  
pp. 226-236 ◽  
Author(s):  
Michel Chrétien ◽  
Claude Gilardeau
Keyword(s):  
Amino Acid ◽  
Polyacrylamide Gel Electrophoresis ◽  
Chemical Characterization ◽  
Terminal Amino Acid ◽  
Amino Acid Determination ◽  
Pituitary Glands ◽  
Terminal Amino ◽  
Partial Chemical ◽  
Acid Determination

ABSTRACT A protein isolated from ovine pituitary glands has been purified, and its homogeneity assessed by NH2- and COOH-terminal amino acid determination, ultracentrifugation studies, and polyacrylamide gel electrophoresis after carboxymethylation. Its chemical and immunochemical properties are closely similar to those of beef and pork neurophysins, less similar to those of human neurophysins. It contains no tryptophan (like other neurophysins) or histidine (like all except bovine neurophysin-I and human neurophysins). It has alanine at the NH2-terminus and valine at the COOH-terminus. Its amino acid composition is similar to, but not identical with those of porcine and bovine neurophysins.

Laboratory Methods for the Physico-Chemical Characterization of Recombinant Allergens as Reference Standards

Alergologia ◽  
2020 ◽  
Vol 1 (4) ◽  
pp. 7
Author(s):  
Mariana Vieru ◽  
Florin-Dan Popescu ◽  
Laura Haidar ◽  
Carmen Bunu-Panaitescu
Keyword(s):  
Chemical Characterization ◽  
Reference Standards ◽  
Recombinant Allergens ◽  
Laboratory Methods ◽  
Physico Chemical
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