Molar Adjustment Factor determinational

The molar adjustment factors (re mannitol) were determined directly, and after metha-nolysis in IN HCl/methanol at 85° for 24 hr and 2N HCl/methanoI at 100° for 24 hr. 

Figure 3. Graph of mole ratio against total peak area ratio for the determination of molar adjustment factors (a) shows the standard curve for mannose (b) shows the standard curve for iV-acetylglucosamine determined directly ( ) and after methanoly sis for 24 hr in liV HCl/methanol at 85° ( ) and in 2N HCl/methanol at 100° (O).

Terminal sialic acids are released in a good yield under mild acidic conditions like formic acid, pH 2 (1 h, 70 X), 0.1 N H2SO4 or 0.1 N HCl (1 h, 80 "C) (Schauer 1978). These conditions do not lead to N-deacylation however, 0-deacylation occurs to an extent of about 50%. Mild acid hydrolysis has frequently been chosen to release N,0-acylneuraminic acids from biological materials for identification by g.l.c./m.s. Derivatization procedures are presented in sections II. 3 and II.4. For g.l.c./m.s., see section III.2. Quantitative g.l.c. procedures after pertrimethyl-silylation (section II.4) have been worked out by Casals-Stenzel et al (1975). Because of partial 0-deacylation during hydrolysis and subsequent isolation, quantitative analysis of the various N,0-acylneuraminic acids present in native biological material is still a serious problem. The nonavailability of pure N,0-acylneuraminic acids as standard compounds makes it also difficult to determine reliable molar adjustment factors for g.l.c. analysis. 

Remarks 1. The amount of added internal standard depends on the carbo-hydrate-content in the sialoglycoconjugate 2. When too much acetic anhydride is added, the primary hydroxyl functions of mannitol are 0-acetylated giving rise to an additional small peak in the gas chromatogram. The same holds for the primary hydroxyl function of NeuSAc methyl ester methyl glycoside 3. Molar adjustment factors of monosaccharides except NeuSAc are determined by application of the methanolysis procedure on standard mixtures of sugars and internal standard. For NeuSAc the molar adjustment factor is determined using a... 

We also observed that the PC chains possess a preferred ability to form inclusion compounds with y-CD in solution, when competing with PMMA and PVAc. From the XH NMR spectrum of the coalesced 1 1 1 PC/PMMA/PVAc blend (not shown), the molar ratio of PC PMMA PVAc was determined to actually be 1.6 1 1.4 compared to the initial molar ratio of 1 24 24, respectively, used in solution to form their common y-CD-IC. Despite the initial 1 24 24 PC PMMA PVAc molar ratio in solution, the PC component in the coalesced PC/PMMA/PVAc blend is still prevalent over the PMMA and PVAc components, which indicates that there may be additional factors that govern the inclusion process from a multiguest system. We believe that this very strong preference of the host y-CD molecules for PC chains, rather than the other two possible guests, is due to their different hydrophobicities. Although the final molar ratio of the coalesced ternary blend can be somewhat controlled by modifying the initial molar ratio of polymers in their common solution, our eventual aim is to be able to adjust, as desired, the constituent polymer ratios in coalesced ternary blends. 

For example, the experimental conditions can be adjusted such that the molecular diffusion is the dominating mechanism (high pressure). This can be experimentally confirmed by the validation of the independence of the steady state flux with respect to the total pressure because the total molar concentration c is proportional to the total pressure while the molecular diffusivity is inversely proportional to pressure (eq. 13.2-12). In this regime, eq. (13.2-12) can be used to determine the tortuosity factor if the binary diffusion coefficient D b is known. 

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