title: Multivariate parameter evaluation of pharmaceutically important cellulose ethers.
abstract: A set of nonionic cellulose ethers with varying hydrophobicity and molecular weight has been investigated by principal component analysis (PCA). Several experimental variables such as dynamic surface tension, diffusion coefficient, microviscosity as monitored by a fluorescence probe technique, and intrinsic viscosity are included in the analysis. The experimental variables and observations (polymer fractions) are analyzed in models with good predictive capacities. The apparent equilibrium surface tension correlates to the cloud point and to the critical aggregation concentration in the presence of surfactant. The microviscosity is shown to be a predictive parameter for the degree of hydrophobic substitution. The irreversible process of dynamic surface tension is dependent on the diffusion coefficient but to an even larger degree on the polymer concentration, which is well illustrated by the PCA models.
authors.affiliation: Physical Pharmaceutical Chemistry, Uppsala University, Uppsala Biomedical Centre, Box 574, 751 23 Uppsala, Sweden, and SPOC, UF3A1, Pharmacia & Upjohn, 751 82 Uppsala.
authors.forename: B
authors.initials: B
authors.lastname: Persson
authors.forename: H
authors.initials: H
authors.lastname: Evertsson
authors.forename: R
authors.initials: R
authors.lastname: Bergman
authors.forename: L O
authors.initials: LO
authors.lastname: Sundelöf
mesh_terms: D000465:Algorithms; D002482:Cellulose / Q000737:chemistry*; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D004058:Diffusion; D004987:Ethers / Q000737:chemistry; D008956:Models, Chemical; D008970:Molecular Weight; D015999:Multivariate Analysis; D012995:Solubility; D013500:Surface Tension; D013501:Surface-Active Agents; D014783:Viscosity
chemical_list: D004987:Ethers; D013501:Surface-Active Agents; D002482:Cellulose