Effects of temperature and mobile-phase composition on retentions in column liquid chromatography. [Hydroxyl-terminated polybutadiene]

Technical Report · Sun Aug 01 00:00:00 EDT 1982

OSTI ID:5040976

Hsu, A

Binary-additive mobile phase systems were investigated for a more exact control over chromatography. If the mobile phase was nonpolar binary solvents (e.g., n-hexane and dichloromethane), trace amounts of THF and/or ACN could be added to control solute retentions as a function of solvent composition. Temperature also plays an important role in the coverage of modifier molecules on the surface of the adsorbent. Higher efficiencies were obtained at lower temperatures. For chromatographic systems having large extra-column volumes, higher column temperature will also reduce column efficiency. Solvophobic effects and polar-group selectivity control the chromatographic behavior of phenols in reversed-phase liquid chromatography (RPLC). The former effect predominates with the THF system, and the latter with the MeOH system. Substituent groups decrease the hydrophobic effect of phenols in aqueous media. However, owing to steric effects, ortho-substituted phenols usually eluted later. Separation of the phenols was also found with 35% MeOH/H/sub 2/O eluent. Application of window diagrams led to baseline separation with 22% THF/H/sub 2/O. Optimum column temperature was 42/sup 0/C with a Zorbax C8 microbore column. The enthalpy-entropy compensation principle was applied to the retention data observed with reversed-phase systems. Relative retention data were found to provide a more consistent compensation temperature. RPLC was shown to be useful in the separation of high molecular-weight compounds such as hydroxyl-terminated polybutadiene (HTPB). HMDS-treated HTPB eluted without difficulty from silical gel. Sample overload can provide unique separations in GPC. (DLC)

• Research Organization: Ohio State Univ. Research Foundation, Columbus (USA). Dept. of Chemistry
• DOE Contract Number: AC02-80ER10554
• OSTI ID: 5040976
• Report Number(s): DOE/ER/10554-21; ON: DE82020756
• Resource Relation: Other Information: Thesis
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
LIQUID COLUMN CHROMATOGRAPHY
ORGANIC POLYMERS
PHENOLS
POLYCYCLIC AROMATIC HYDROCARBONS
ACETONITRILE
METHANOL
SEPARATION PROCESSES
TEMPERATURE DEPENDENCE
TETRAHYDROFURAN
ALCOHOLS
AROMATICS
CHROMATOGRAPHY
FURANS
HETEROCYCLIC COMPOUNDS
HYDROCARBONS
HYDROXY COMPOUNDS
NITRILES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
POLYMERS
400105* - Separation Procedures