Molecular weight physicochemical methods

Solution Polymers. Acryflc solution polymers are usually characterized by their composition, solids content, viscosity, molecular weight, glass-transition temperature, and solvent. The compositions of acryflc polymers are most readily determined by physicochemical methods such as spectroscopy, pyrolytic gas—liquid chromatography, and refractive index measurements (97,158). The solids content of acryflc polymers is determined by dilution followed by solvent evaporation to constant weight. Viscosities are most conveniently determined with a Brookfield viscometer, molecular weight by intrinsic viscosity (158), and glass-transition temperature by calorimetry. 

Partitioning or cell-based methods provide an absolute measure of the chemical space covered by a collection of compounds. They are based on the definition of a low-dimensional chemistry space, for example, one based on a small number of physicochemical properties such as molecular weight, calculated logP, and number of hydrogen bond donors [45]. Each property defines an axis of the chemistry-space. The range of values for each property is divided into a set of bins, and the combinatorial product of all bins then defines the set of cells or partitions that make up the space. 

Estimation is easier and less time-consuming because use is made of empirical relationships between the BCF and physicochemical properties of the compound, such as water solubility (S) [42-48], Km, (solid organic carbon/water partition coefficient) [48], Kmw (membrane water partition coefficient), iipw (liposome water partition coefficient) [49], critical micelle concentration (CMC) [45], steric factors, molecular weight [47,48], and others. The most common regression method is the estimation of BCF from the octanol-water partition coefficient (Kovl) [18,42,44-48,50,51],... 

Different water-soluble cellulose derivatives have been used for the determination of endocellulase activities. Carboxymethylcellulose (CMC) has been proposed as substrate and recently Almin et al. (3) have improved their method for the calculation of endocellulase activities, using a medium-molecular-weight CMC (Mv = 299,000 and Mw = 142,000) with well-defined physicochemical properties. No corrections... 

The molecular weight is an intrinsic property of biomolecules. Sedimentation velocity is one of physicochemical methods which have been employed to determine molecular weights of many biomacromolecules. The molecular weight (M) of a biomacromolecule can be computed according to the Svelberg equation ... 

In this chapter we describe some methods used to determine the kinetics of the action of hyaluronidase. Thble 2 presents a survey of the Michaelis-Menten constants (Km) of the action of hyaluronidase on hyaluronan and chondiootin sulfate obtained using different methods. These assays usually make use of hyaluronan as a substrate for hyaluionidase. Various sources of hyalmonan are employed, but these arbitrates have different physicochemical properties (molecular weight intrinsic viscosity). Payan el al [130] investigated the action of Streptmnyces hyahnonidase on hyaluronan from several sources. 

JEV-loaded poly(lactide) (PLA) lamellar and PLG microspheres were successfully prepared with low-molecular-weight PLA by the precipitate method and with 6% w/v PLG in the organic phase, 10% w/v PVP, and 5% w/v NaCl in the continuous phase by using a w/o/w emulsion/solvent extraction technique, respectively [233], The JEV incorporation, physicochemical characterization data, and animal results obtained in this study may be relevant in optimizing the vaccine incorporation and delivery properties of these potential vaccine targeting carriers. 

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