Gas-liquid chromatography of hydrolyzates

Starch Snack foods Neotec 6350 scanning spectrometer, reflectance Gas liquid chromatography of hydrolyzed starch 8... 

The malonaldehyde thus formed can be estimated quantitatively by the thiobarbituric acid method (58, 59). As a control of the method s reliability, we used, as primary standard, 1, 3, 3-tri-ethoxypropene (46, 47) purified by gas-liquid chromatography (56) and hydrolyzed to malonaldehyde at room temperature with IN sulfuric acid. The molar... 

The structures of many oligosaccharide chains can be elucidated by gas-liquid chromatography, mass spectrometry, and high-resolution NMR spectrometry. Glycosidases hydrolyze specific linkages in oligosaccharides and are used to explore both the structures and functions of glycoproteins. 

Originally, Edman hydrolyzed the PTH-amino acids and identified the free amino acids by paper chromatography 0. Since not all of the amino acids are sufficiently resistant to this treatment Edman and Soquist subsequently devised methods for the direct identification of the PTH-amino acids. Paper chromatography has now generally been abandoned in favour of the more sensitive thin layer chromatography Recently, gas-liquid chromatography... 

Gas-liquid chromatography (GLC) has notTeen employed for the analysis of flavanone glycosides because they are non-volatile and thermally unstable. One GLC method (28) has been developed for the analysis of the flavanone aglycones. However, the method is extremely time consuming in that the samples must be extracted, hydrolyzed and derivatized before analysis. Furthermore, the procedure cannot distinguish between bitter and nonbitter flavonoids. 

The phenylthiohydantoins may be identified directly by thin layer chromatography or gas-liquid chromatography (see below). Alternatively, they can be hydrolyzed at 140°C in 5.7 N glass-distilled HCl in vacuo (see 2.1.2 for other details) in the presence of phenol (1 drop of 5 % phenol in water) to regenerate the amino acid, which can be identified with an analyzer or by pH 1.9 electrophoresis. The regeneration is not quantitative, and several amino acids, particularly serine and threonine, are usually destroyed completely. 

After purification of human serum bile acids on an Amberlyst A-26 anion e.xchanger, Sjovall and co-workers (31, 120, 121) hydrolyzed the concentrated bile acids in alkali and extracted the free acids with ethyl acetate. After methylation, the methyl cholanoates were purified on an aluminum oxide column. The bile acid fraction then obtained was subjected to gas-liquid chromatography on CNSi columns after conversion to trifluoroacetate... 

Using reference compounds Sandberg et al. (1956) were able to quantitate hydrolyzed serum bile acids by means of gas-liquid chromatography. 

Some of the peptides remain incompletely hydrolyzed, thereby tying up amino acids which should be measured. Following the hydrolysis of the protein, the resulting amino acids are commonly separated by ion-exchange chromatography and subsequently measured by colorimetric techniques or by gas-liquid chromatography. 

A dry and argon-flushed flask is charged with zinc dust (Aldrich, 325 mesh, 0.820 g, 12.5 mmol, activated by 1,2-dibromoethane). DMF (2 mL) is added and the suspension heated to 45-50 °C. A solution of 2-iodophenyl cyclohexyl ketone (226, 1.50 g, 4.77 mmol) and undecene as internal standard (0.05 g) in DMF (4 mL) is added over 40 min. The mixture is stirred 4 h at 45-50 °C, until gas-liquid chromatography (GLC) analysis of hydrolyzed reaction aliquots show less than 5% remaining aryl iodide. The reaction mixture is allowed to settle and the supernatant solution of the organozinc iodide 227 is canulated into a second flask containing a solution of dry LiCl (0.424 g, 10.0 mmol) and CuCN (0.45 g, 5.0 mmol) in THF (6 mL) at -70 °C. A solution of tert-butyl a-(bromomethyl)acrylate (0.35 g, 1.73 mmol) is added. The reaction mixture is stirred for 1 h at 0 °C. Standard workup and purification by flash chromatography provide 225 (0.467 g, 72%). ... 

Certain classes of lipids are susceptible to degradation under specific conditions. For example, all ester-linked fatty acids in triacylglycerols, phospholipids, and sterol esters are released by mild acid or alkaline treatment, and somewhat harsher hydrolysis conditions release amide-bound fatty acids from sphingolipids. Enzymes that specifically hydrolyze certain lipids are also useful in the determination of lipid structure. Phospholipases A, C, and D (Fig. 10-15) each split particular bonds in phospholipids and yield products with characteristic solubilities and chromatographic behaviors. Phospholipase C, for example, releases a water-soluble phosphoryl alcohol (such as phosphocholine from phosphatidylcholine) and a chloroform-soluble diacylglycerol, each of which can be characterized separately to determine the structure of the intact phospholipid. The combination of specific hydrolysis with characterization of the products by thin-layer, gas-liquid, or high-performance liquid chromatography often allows determination of a lipid structure. 

Segmented gas-liquid (Taylor) flow was used for particle synthesis within the liquid slugs. Tetraethylorthosilicate in ethanol was hydrolyzed by a solution of ammonia, water and ethanol (Stober synthesis) [329]. The resulting silicic acid monomer Si (OH)4 is then converted by polycondensation to colloidal monodisperse silica nanoparticles. These particles have industrial application, for example, in pigments, catalysts, sensors, health care, antireflective coatings and chromatography. 

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