Yoshiyuki Mukoyama

Elution Behavior of Polyethylene Glycols on a Hydrophilic Polymer Gel Column Used for Size Exclusion Chromatography

Abstract Water, methanol, tetrahydrofurar. and their mixtures were used as mobile phases and the relationship between retention volumes of polyethylene glycol (PEG) and the composition of the mobile phases on a hydrophilic polymethacrylate gel column was investigated. The column packed with this polymer gel could be used with both polar and non-polar organic solvents as well as aqueous solvents. Retention volume of PEG having the same molecular weight changed with changing the composition of the mobile phase. The change of molecular size of PEG with changing the composition of the mobile phase was small compared to the difference in retention volume, and PEG samples were considered to be separated mainly by size exclusion, secondary effects being superimposed. In order to calculate molecular weight averages of PEG, the adequate selection of the mobile phase which minimizes the peak width of PEG is important and the recommended combination of PEG and the mobile phase with the column used here for PEG are F...

High-performance size-exclusion chromatography of poly- and oligoethylene terephthalate using a mixture of hexafluoroisopropanol and chloroform as the mobile phase

Abstract Solvent systems using a mixture of hexafluoroisopropanol (HFIP) and chloroform (CHCl3) were developed for the analysis of polyethylene terephthalate (PET) and its oligomers by high-performance size-exclusion chromatography (SEC) at room temperature (25°C). The molecular weight distribution of PET and PET film were determined using HFIP-CHCl3 (1:9) and the SEC calibration graph of polystyrenes, which are insoluble in HFIP. These mixed solvents also had considerable advantages with regard to cost reduction and safety in comparison with HFIP alone.

Elution behaviour of polyamic acid and polyamide-imide in size-exclusion chromatography

Abstract The causes of the peculiarities of the elution behaviour of thermoresistant resins, when N,N-dimethylformamide (DMF) is used as the mobile phase were investigated. In order to establish whether the peculiarities are caused by the properties of DMF, by the interactions between the stationary phase and DMF, or by the generation of specific properties of the solutes in DMF, tetrahydrofuran (THF)-soluble polyamic and polyamide—imide resins were prepared. Two stationary phases, hydrophobic polystyrene gel and hydrophilic polymer gel, were used and DMF, THF and a mixture of DMF and THF with or without H 3 PO 4 and LiBr were used as the mobile phases. The peculiarities are discussed from the point of dissociation of carboxylic groups of the solutes and of the hydrophilic stationary phase. Adsorption of the resins on the columns or early elution from the columns were prevented by the addition of H 3 PO 4 and early elution of the neutral polyamide—imide from the column was prevented by the addition of LiBr. The early elution of the resins was not due to the intramolecular chain expansion of the resins in DMF, but to the interactions between carboxylic groups of the resins and of the hydrophilic polymer gels. The addition of H 3 PO 4 suppressed the dissociation of carboxylic groups of the resins. DMF partially controls the dissociation of the carboxylic groups.

Combination of Size Exclusion and Adsorption Phenomena on a Hydrophilic Polymer Gel Column Using Organic Solvents

Abstract Elution behavior of alkylbenzenes, phthalate esters, oligostyrenes, and prepolymers of epoxy resins and methylated melamine-formaldehyde resins has been investigated on a column packed with hydrophilic polyhydroxyethyl methacrylate gels using tetrahydrofuran (THF), methanol, and mixtures of THF and methanol or n-hexane as the mobile phases. Size-exclusion effect was predominant when THF was used as the mobile phase and adsorption interactions between solutes and the gels superimposed the size-exclusion effect when methanol or mixtures of THF and methanol or n-hexane was the mobile phase. The gel-THF system was assumed to be SEC. The addition of methanol or n-hexane to THF in the mobile phase retarded the elution of solutes. The combination of size exclusion and adsorption modes in the same column was possible by changing composition of the mobile phase and resolution of some peaks was improved than by SEC alone. The peak identification by the present system is also improved than by SEC.