title: Ion-exclusion chromatographic separations of C1-C6 aliphatic carboxylic acids on a sulfonated styrene-divinylbenzene co-polymer resin column with 5-methylhexanoic acid as eluent.
abstract: The application of C7 aliphatic carboxylic acids (heptanoic, 2-methylhexanoic, 5-methylhexanoic and 2,2-dimethyl-n-valeric acids) as eluents in ion-exclusion chromatography with conductimetric detection for C1-C6 aliphatic carboxylic acids (formic, acetic, propionic, isobutyric, butyric, isovaleric, valeric, isocaproic and caproic acids) was carried out using a highly sulfonated styrene-divinylbenzene co-polymer resin (TSKgel SCX) in the H+ form as a stationary phase. When using 0.05 mM sulfuric acid at pH 4.0 as the eluent, peak shapes of hydrophobic carboxylic acids (isovaleric, valeric, isocaproic and caproic acids) were tailed strongly. In contrast, when using 1 mM these C7 carboxylic acids at pH ca. 4 as the eluents, although system peaks (vacant peaks) corresponding to these C7 carboxylic acids appeared, peak shapes of these hydrophobic acids were improved drastically. Excellent simultaneous separation and relatively high sensitive conductimetric detection for these C1-C6 aliphatic carboxylic acids were achieved in 25 min on the TSKgel SCX column (150 x 6 mm I.D.) using 1 mM 5-methylhexanoic acid at pH 4.0 as the eluent.
authors.affiliation: Ceramics Research Institute, National Institute of Advanced Industrial Science and Technology 2266-98 Anagahora, Simoshidami, Moriyama-ku, Nagoya 463-8560, Japan. kazu.ohta@aist.go.jp
authors.forename: Kazutoku
authors.initials: K
authors.lastname: Ohta
authors.forename: Atsuya
authors.initials: A
authors.lastname: Towata
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Ohashi
mesh_terms: D019817:Benzoic Acid; D002208:Caproates; D002264:Carboxylic Acids / Q000302:isolation & purification*; D002852:Chromatography, Ion Exchange / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents; D011108:Polymers; D011137:Polystyrenes; D012680:Sensitivity and Specificity; D055672:Static Electricity; D013451:Sulfonic Acids; D013464:Sulfuric Acids
chemical_list: D002208:Caproates; D002264:Carboxylic Acids; D007202:Indicators and Reagents; D011108:Polymers; D011137:Polystyrenes; D013451:Sulfonic Acids; D013464:Sulfuric Acids; C432006:divinylbenzene-polystyrene copolymer; C060775:methyl caproate; C481311:5-methylhexanoic acid; D019817:Benzoic Acid; C033158:sulfuric acid; C077114:styrenesulfonic acid polymer