Alcohol groups chemical derivatization

Chemical derivatization is a standard procedure for GC-MS analysis of steroid hormones, because steroid hormones are not volatile to go through GC column [1, 6], The major concerns of derivatization reagents for GC-MS analysis of steroid hormones are the completeness of the derivatization reaction and the volatility of hormone derivatives. The typical derivatization reagents for GC-MS samples are silylation reagents, e.g., Af-methyl-Af-trifluorotrimethyl acetamide (MSTFA, [37, 39]) and A,0-bis(trimethylsilyl) trifluoroacetamide (BSTFA, [33]), which react with both alcoholic and phenolic hydroxy groups on steroid hormone molecules. 

Pulsed Plasma Polymerization. Allyl alcohol, allylamine and acrylic acid were polymerized in pulsed plasma to retain a maximum in functionalities in the resulting plasma polymer. The retention of functional groups during the plasma process, introduced by functional-group carrying monomers and followed by deposition to polymer layers, was primarily measured by XPS including the chemical derivatization of these groups as described in Experimental. These layers were also checked for side-products by respective IR spectra. The results are summarized in Table 1. 

Three methods that were used to measure the chemical changes associated with oxidative degradation of polymeric materials are presented. The first method is based on the nuclear activation of lsO in an elastomer that was thermally aged in an, 802 atmosphere. Second, the alcohol groups in a thermally aged elastomer were derivatized with trifluoroacetic anhydride and their concentration measured via 19F NMR spectroscopy. Finally, a respirometer was used to directly measure the oxidative rates of a polyurethane foam as a function of aging temperature. The measurement of the oxidation rates enabled acceleration factors for oxidative degradation of these materials to be calculated. 

The requirement that samples be in the vapor phase used to be a limiting factor in the utility of mass spectrometry because it was frequently necessary to add heat to vaporize samples. Successful vaporization depends on the polarity and molecular mass of the analyte. For small molecules (<1 kDa) polarity is the most important factor, particularly the number of primary amino (-NH2), hydroxyl (-OH), and acidic (-COOH) groups present. When there are two or three of these groups present, heating will frequently destroy compounds before they vaporize, even at reduced pressures. Chemical derivatization, e.g., the conversion of an alcohol to its trimethylsilyl ether or the acetylation of an acid group, can be used to reduce the polarity and increase the volatility of analytes, thereby improving the chances of obtaining useful spectra. 

After establishing the elemental compositions of the carbon fiber surfaces by ESCA, wet chemical derivatizations were carried out to determine the number of -COOH, -COH and -C=0 functional groups on the very outer fiber surface[24]. It is posible to use pentafiuorophenylhydrazine for detecting carbonyl, chloro silanes for alcohol and carbo lic acid groups by pentafluorobromotoluene(fig. 11). 

Poly(vinyl alcohol)-based cation exchangers are currentiy offered by Metrohm (Herisau, Switzerland) and Showa Denko (Tokyo, Japan). The respective product from Metrohm is the carboxylate-based Metrosep C3, which belongs to the group of chemically derivatized polymers [17]. Metrosep C3 is offered in three... 

CDs are cyclic oligosaccharides containing 6, 7, or 8 glucopyranose units, referred to as a-, (3-, or y-CD, respectively. Each glucose unit contains two secondary alcohols at C-2 and C-3 and a primary alcohol at the C-6 position, providing 18-24 sites for chemical modification and derivatization (Fig. 2). Numerous derivatives have been prepared and described in the literature, but because of all the possible derivatives and positional and regioisomers, appropriate nomenclature must be used. The nomenclature should include at a minimum, the parent CD (a, (3, or y-CD) and the type and number of substituents. The substituents are usually noted by an abbreviation placed before the parent CD. Further description of the substituent group can be included with... 

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