Ken Hosoya

Reversed-Phase Chromatographic Properties of Monodispersed Macroporous Particles of Poly(styrene-divinylbenzene) Prepared by a Multi-Step Swelling and Polymerization Method

Abstract Monodispersed macroporous poly(styrene-divinylbenzene) particles in a 5-6 μm size range were prepared by a multi-step swelling and polymerization method with toluene as the porogenic solvent, and their properties were examined. The particles were found to possess relatively broad pore size distributions. HPLC columns packed with the monodispersed particles show good efficiencies and low column pressure drops in a reversed-phase chromatographic mode.

Efficiency of porous hydrophilic polymer-based packing materials in chromatographic analysis of drugs existing with polypeptide

SummaryA size monodispersed restricted-access polymeric packing material has been prepared through a simple and easy one-step method of co-polymerization of glycerol monomethacrylate and glycerol dimethacrylate with cyclohexanol as prorogen. A typical seeded polymerization (two step swelling and polymerization method) in an aqueous medium gave a 90 % yield of porous beads which could be utilized as a packing material in high performance liquid chromatography (HPLC) without any size classification due to the excellent size monodispersity. A BET measurement and size exclusion chromatography in either tetrahydrofuran or water revealed that the prepared material had only small pores (around 100 Å in diameter). It showed ample hydrophobicity for the separation of hydrophilic drug molecules in 10% aqueous acetonitrile buffer, while polypeptides such as bovine serum albumin were excluded and eluted before the void volume of the column with quantitative recovery.

Preparation and chromatographic properties of uniform size cross-linked macroporous poly(vinyl p-tert.-butylbenzoate) beads: Evaluation of preferential retention toward organohalides

Abstract Uniform size cross-linked macroporous poly(vinyl p - tert .-butyl benzoate) beads (VPTBBA) were prepared by a two-step swelling and polymerization method. VPTBBA was obtained in 78% yield and utilized as a packing material in high-performance liquid chromatography. The specific surface area of VPTBBA, which had a polymodal broad pore size distribution, was calculated as 314 m 2 /g by the BET method. In the reversed-phase mode, VPTBBA showed preferential retention towards some aromatic and/or aliphatic halogenated compounds. In a comparison of its chromatographic properties with those on other packing materials such as two kinds of poly(vinyl carboxylate)-based beads, poly(styrene—divinylbenzene) beads and poly(methyl methacrylate—ethylene dimethacrylate) beads, and a silica-based monomeric C 18 stationary phase, the selectivities on VPTBBA can be explained mainly based on both dipole—dipole interactions caused by the π-acidic phenyl group of VPTBBA and preferential retention towards planer solutes. Moreover, the relatively hydrophobic tert .-butyl groups contribute to steric selectivity and to the total hydrophobicity of the packing material.

Photodecomposition of 1,2,3,4- and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in water-alcohol media on a solid support

We used a hydrophobic solid support, octadecylsilylated silica gel (C18), packed in a quartz column as a reaction medium for the photolysis of 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) and 1,2,3,4-tetrachlorodibenzo-p-dioxin (1,2,3,4-TCDD). When we exposed the column to a 450 W UV lamp, the adsorbed 1,2,3,4-TCDD or 2,3,7,8-TCDD in 10% 2-propanol/water decomposed completely in 20 minutes and 5 minutes, respectively. The large estimated partition coefficient of 1,2,3,4-TCDD in 10% 2-propanol/water (> 1000) indicates that on the C18 stationary phase, both the saturated hydrocarbon chains and the absorbed 2-propanol may act as proton donors and accelerate the photolysis. In direct sunlight, the adsorbed 1,2,3,4-TCDD in 10% 2-propanol/water decomposed much faster than in a nonaqueous solvent (50% 2-propanol/methanol). This solvent effect is advantageous for the practical use of the C18 photolysis process in aqueous waste treatment. We have demonstrated that complete C18 trapping with continuous photodecomposition of TCDD contained in an aqueous alcohol waste is possible.

Influence of Pore Size and Pore Size Distribution of Polymer-Based Packing Materials on Chromatographic Separation of Carbon Clusters

Abstract Size monodispersed poly(styrene-divinylbenzene) particles with a variety of pore size and pore size distribution were prepared by a multi-step swelling and polymerization method and utilized as packing materials in high performance liquid chromatography (HPLC). As an application of these packing materials, separation of carbon clusters C60 and C70 were examined in a mixture of hexane and benzene and an influence of the pore size and the pore size distribution of the polymer-based packing materials on the separation was investigated. Although carbon clusters are sterically bulky molecules, packing materials with smaller pores showed better separation than those with larger pores. Completely separated peaks and the good peak shape suggest possible isolation of carbon clusters on relatively cheap polymer-based packing materials.