A long alkyl group like C30 (triacontyl group) phase has been known to be more suitable than a conventional C18 phase for separation of hydrophobic structurally related isomers such as vitamin E or vitamin K1. However, in many cases a C30 column shows a tailing peak. This tailing is considered to be a reason why C30 ligand density is too high. We have reported optimization for a pore diameter of the superficially porous silica and a ligand density of C30 phase [1]. In this study, the optimized C30 phase was evaluated to compare with C18 phase or the other C30 phase. Regarding separation of cis and trans-vitamin K1, the optimized C30 phase showed better separation than the other C30 phase while a C18 phase could not separate them. The higher temperature, the worse separation of isomers. The optimized C30 phase could separate cis and trans-vitamin k1 at over 30 degree Celsius although the other C30 phase couldn’t. This C30 phase was applied for separation of some structural related isomers, and showed higher resolution of isomers than conventional C18 phase.
]]>A long alkyl group like C30 (triacontyl group) has been known tobe more suitable than a conventional C18 phase for separation of hydrophobic structurally related isomers such as vitamin E or vitamin K1. In this study, separation factor of beta-tocopherol and gamma-tocopherol which were structurally related isomers was evaluated to vary both a pore diameter of the superficially porous silica and a ligand density of the C30 group. Regarding a pore diameter, 12 nm showed the largest separation factor of beta and gamma-tocopherol among 10nm, 12 nm and 16 nm. Regarding a ligand density, the higher a ligand density, the larger a separation factor of beta and gamma-tocopherol. However, when a ligand density was too high, much high hydrophobicity caused peak tailing and a drop of theoretical plate. The most suitable ligand density existed for the highest resolution. Finally separation of cis and trans-vitamin K1 was compared and the same result as separation of beta and gamma-tocopherol was obtained.
]]>A column packed with 2.6 μmor 2.7 μmsuperficially porous particle has been widely used on HPLC and UHPLC, because it showed not only excellent column efficiency but also lower back pressure than sub-2 um column. Recently 2.0 μmand less than 2.0 μmsuperficially porous C18 columns were developed and have been available. In this study, 3 kinds of 2.0 μmand 1.7 μmsuperficially porous C18s and one totally porous hybrid C18, one totally porous monodisperse C18 were evaluated regarding efficiency, hydrogen bonding capacity, hydrophobicity, steric selectivity as well as peak shape of acidic, basic and metal chelating compounds. Compared C18 columns were SunShellC18 2 μm, AscentisExpress C18 2 μm, KinetexC18 1.7 μm, AcquityBEH C18 1.7 μmand Titan C18 1.9 μm. Furthermore, efficiency loss due to frictional heating which yielded under high pressure and at high flow rate was observed. This efficiency loss was larger for a totally porous C18 than a superficially porous C18. Especially totally porous hybrid C18 showed the largest efficiency loss because of the lowest thermal conductivity
]]>A column packed with 2.6 μmor 2.7 μmsuperficially porous particle has been widely used on HPLC and UHPLC, because it showed not only excellent column efficiency but also lower back pressure than sub-2 um column. Recently 2.0 μmand less than 2.0 μmsuperficially porous C18 columns were developed and have been available. In this study, 3 kinds of 2.0 μmand 1.7 μmsuperficially porous C18s and one totally porous hybrid C18, one totally porous monodisperse C18 were evaluated regarding efficiency, hydrogen bonding capacity, hydrophobicity, steric selectivity as well as peak shape of acidic, basic and metal chelating compounds. Compared C18 columns were SunShellC18 2 μm, AscentisExpress C18 2 μm, KinetexC18 1.7 μm, AcquityBEH C18 1.7 μmand Titan C18 1.9 μm. Furthermore, efficiency loss due to frictional heating which yielded under high pressure and at high flow rate was observed. This efficiency loss was larger for a totally porous C18 than a superficially porous C18. Especially totally porous hybrid C18 showed the largest efficiency loss because of the lowest thermal conductivity
]]>A long alkyl group like C30 (triacontyl group) has been known tobe more suitable than a conventional C18 phase for separation of hydrophobic structurally related isomers such as vitamin E or vitamin K1. In this study, separation factor of beta-tocopherol and gamma-tocopherol which were structurally related isomers was evaluated to vary both a pore diameter of the superficially porous silica and a ligand density of the C30 group. Regarding a pore diameter, 12 nm showed the largest separation factor of beta and gamma-tocopherol among 10nm, 12 nm and 16 nm. Regarding a ligand density, the higher a ligand density, the larger a separation factor of beta and gamma-tocopherol. However, when a ligand density was too high, much high hydrophobicity caused peak tailing and a drop of theoretical plate. The most suitable ligand density existed for the highest resolution. Finally separation of cis and trans-vitamin K1 was compared and the same result as separation of beta and gamma-tocopherol was obtained
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