Glycerol determination

Ribitol and Glycerol Determine as directed in the Assay. Identify the peak area responses for glycerol and ribitol in the chromatogram of the Assay Preparation by comparison with the chromatogram of the Standard Preparation, and calculate the percentage of glycerol and ribitol by the equations... 

Conv. GLY, glycerol conversion sel. DHA, selectivity to dihydroxyacetone yield DHA, molar yield (%) [moles of DHA/100 moles of glycerol] determined by GC analysis. Conditions ((unless stated otherwise) glycerol (1.0 mmol), Cu(II) complex 19.3 (5.0 p.mol), r=25°C, solvent acetonitrile/water. 

MonoSik, R., Ukropcova, D., Stredansky, M., and Sturdik, E. (2012) Multienzy-matic amperometric biosensor based on gold and nanocomposite planar electrodes for glycerol determination in wine. Anal. Biochem., 421, 256-261. Bruggink, A., Schoevaart, R., and Kieboom, T. (2003) Concepts of nature in organic synthesis cascade catalysis and multistep conversions in concert. Org. Process Res. Dev., 7, 622-640. 

Kronka, E. A. M., P. R. Borges, R. Latanze, A. P. S., Paim, and B. F. Reis. 2001. Multicommutated flow system for glycerol determination in alcoholic fermentation juice using enzymatic reaction and spectrophotometry. J. Flow Injection Anal. 18 132-138. 

More recently, fractionation according to unsaturation has been obtained by TLC on silver nitrate-impregnated plates (Barrett et al., 1962, 1963 De Vries, 1962 De Vries and Jurriens, 1964 Jurriens et al., 1964a,b), and quantitation has been achieved by densitometry (Purdy and Truter, 1962a,b) or by glycerol determination (Jurriens et al., 1964a) colorimetry (Hirsch, 1961) or GLC of the methyl esters in presence of a suitable standard (Blank et al., 1965). 

I. DETERMINATION OF NUMBER OF ACETYL GROUPS IN TRIACETIN (TRIACETYL-GLYCEROL) C3H6(O COCH3)3. Molecular Weight, 218. 

Animal fats and vegetable oils are triacylglycerols, or triesters, formed from the reaction of glycerol (1,2, 3-propanetriol) with three long-chain fatty acids. One of the methods used to characterize a fat or an oil is a determination of its saponification number. When treated with boiling aqueous KOH, an ester is saponified into the parent alcohol and fatty acids (as carboxylate ions). The saponification number is the number of milligrams of KOH required to saponify 1.000 g of the fat or oil. In a typical analysis, a 2.085-g sample of butter is added to 25.00 ml of 0.5131 M KOH. After saponification is complete, the excess KOH is back titrated with 10.26 ml of0.5000 M HCl. What is the saponification number for this sample of butter ... 

The identity of the moiety (other than glycerol) esterified to the phosphoric group determines the specific phosphoHpid compound. The three most common phosphoHpids in commercial oils are phosphatidylcholine or lecithin [8002-45-5] (3a), phosphatidylethanolamine or cephalin [4537-76-2] (3b), and phosphatidjlinositol [28154-49-7] (3c). These materials are important constituents of plant and animal membranes. The phosphoHpid content of oils varies widely. Laurie oils, such as coconut and palm kernel, contain a few hundredths of a percent. Most oils contain 0.1 to 0.5%. Com and cottonseed oils contain almost 1% whereas soybean oil can vary from 1 to 3% phosphoHpid. Some phosphoHpids, such as dipaLmitoylphosphatidylcholine (R = R = palmitic R" = choline), form bilayer stmetures known as vesicles or Hposomes. The bdayer stmeture can microencapsulate solutes and transport them through systems where they would normally be degraded. This property allows their use in dmg deHvery systems (qv) (8). 

The concentration of distilled glycerol is easily determined from its specific gravity (15) by the pycnometer method (16) with a precision of 0.02%. Deterrnination of the refractive index also is employed (but not as widely) to measure glycerol concentration to 0.1% (17). 

The preferred method of determining water in glycerol is by the Kad Fischer volumetric method (18). Water can also be determined by a special quantitative distillation in which the distilled water is absorbed by anhydrous magnesium perchlorate (19). Other tests such as ash, alkalinity or acidity, sodium chloride, and total organic residue are included in AOCS methods (13,16,18). 

Alcohols.—It may be a liquid alcohol (methyl, ethyl, propyl, etc., glycerol, benzyl) or a solution of it in nater. In the former case its boiling-point will have already been determined. Itttiay be fiirthei identified (1) by converting it into the benzoic... 

Hall and Harvey prefer to determine glyceryl acetate in essential oils by a method in which the glycerol is separated and weighed. This method is as follows —... 

The strong interactions between the water molecules also become obvious from NMR measurements by Tsujii et al..57) 13C-NMR experiments were used for determining the microviscosity of water in reversed micelles of dodecylammonium-propionate with 13C glycine cosolubilized. It was found that the apparent viscosity of the water-pool corresponds to the viscosity of a 78 % aqueous glycerol solution, obviously as a consequence of the extended network formation by strong hydrogen bonding. 

Media used for laboratory studies of exopolysaccharide production may vary considerably from industrial production media. In laboratory studies pure substrates such as glucose, sucrose and glycerol, can be used to determine exopolysaccharide yields. In industrial production the main factors that influence the decision as to which substrate to use are ... 

Starting with the AfH°m for H20(1) and for C02(g), Ar//° for many organic compounds can be determined. For example, Bastos et air have measured the enthalpy of combustion of glycerol OHrO.v They obtain a value at T= 298.15 K of... 

The changes in osmotic coefficients with temperature and concentration make it difficult to solve the above equations accurately, but accurate determinations of the composition and relative amounts of the concentrated liquid and ice can be made from phase diagrams which are plots of the freezing points of solutions versus their concentration. From these, it is possible to determine the exact NaCl concentration at any temperature. Examples are shown in Figure 9 for solutions of 0 to 2.0 M glycerol in 0.15 M NaCl. This figure nicely illustrates how the presence of glycerol reduces the concentration of NaCl in the residual unfrozen solution. 

Importantly, there was a general marked selectivity for inhibition of influenza A over influenza B viral sialidases in the carboxamide series (e.g. as seen with 27) (Smith et al. 1996, 1998), determined from crystallographic and molecular modelling studies (Smith et al. 1996 Taylor et al. 1998) to be due to the relative abilities of each of the sialidases to absorb the structural changes required to accommodate the hydrophobic alkyl chains in the glycerol side-chain binding pocket. In influenza... 

In the wine industry, FTIR has become a useful technique for rapid analysis of industrial-grade glycerol adulteration, polymeric mannose, organic acids, and varietal authenticity. Urbano Cuadrado et al. (2005) studied the applicability of spectroscopic techniques in the near- and mid-infrared frequencies to determine multiple wine parameters alcoholic degree, volumic mass, total acidity, total polyphenol index, glycerol, and total sulfur dioxide in a much more efficient approach than standard and reference methods in terms of time, reagent, and operation errors. 

Soumarmon et al. [90,91] determined in an octylglycoside solubilized H,K-ATPase preparation by gel filtration and glycerol gradient centrifugation molecular masses between 390 and 420 kDa for the holomeric enzyme. 

---