Separation of C_1-C_5 aliphatic carboxylic acids on a highly sulfonated styrene-divinylbenzene copolymer resin column with a C_6 aliphatic arboxylic acid solution as the mobile phase

摘要

Simultaneous separation of C_1-C_5 aliphatic carboxylic acids (formic, acetic, propionic, iso-butyric, butyric,iso-valeric and valeric acids) on a highly sulfonated styrene-divinylbenzene copolymer resin column (TSKgel SCX, 150 mm X 6 mm i.d.) was performed with C_6 aliphatic carboxylic acids (3-methyl-n-valeric,iso-caproic and caproic acids) solutions as the mobile phases. Using 0.05 mM sulfuric acid at pH 4.0 as the mobile phase, although good separation of these C_1-C_5 acids was achieved, peaks of the C_5 acids (iso-valeric and valeric acids) with large hydrophobicity tailed strongly. In contrast, using 1 mM C_6 acids at pH 4.0 as the mobile phases, although vacant peaks corresponding to the C_6 acids in the mobile phase appeared, the peak shapes of the C_5 acids were improved greatly. Excellent simultaneous separation, symmetrical peaks and relatively high-sensitivity conductimetric detection for these C_1-C_5 acids were achieved on the TSKgel SCX column in 15 min with 1 mM iso-caproic acid at pH 4.0 as the mobile phase.