title: Vacancy ion-exclusion chromatography of carboxylic acids on a weakly acidic cation-exchange resin.
abstract: In this preliminary study, a new approach to ion-exclusion chromatography is proposed to overcome the relatively poor conductivity detection response which occurs in ion-exclusion chromatography when acids are added to the eluent in order to improve peak shape. This approach, termed vacancy ion-exclusion chromatography, requires the sample to be used as eluent and a sample of water to be injected onto a weakly acidic cation-exchange column (TSKgel OApak-A). Vacancy peaks for each of the analytes appear at the retention times of these analytes. Highly sensitive conductivity detection is possible and sharp, well-shaped peaks are produced, leading to efficient separations. Retention times were found to be affected by the concentration of the analytes in the eluent, and also by the presence of an organic modifier such as methanol in the eluent. Detection limits for oxalic, formic, acetic, propionic, butyric and valeric acids were 0.1, 0.2, 0.3, 0.3, 0.4 and 0.5 microM, respectively, and linear ranges for some acids extended over two orders of magnitude. Precision values for retention times were 0.21% and for peak areas were <1.90%. The vacancy ion-exclusion chromatography method was found to give detection responses four to 10 times higher than conventional ion-exclusion chromatography using sulfuric acid eluent and two to five times higher than conventional ion-exclusion chromatography using benzoic acid eluent.
authors.affiliation: National Institute of Advanced Industrial Science and Technology, and Graduate School of Engineering, Chubu University, Seto, Japan. kazuhiko-tanaka@aist.go.jp
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Tanaka
authors.forename: Ming-Yu
authors.initials: MY
authors.lastname: Ding
authors.forename: Murad I H
authors.initials: MI
authors.lastname: Helaleh
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Taoda
authors.forename: Hayato
authors.initials: H
authors.lastname: Takahashi
authors.forename: Wenzhi
authors.initials: W
authors.lastname: Hu
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Hasebe
authors.forename: Paul R
authors.initials: PR
authors.lastname: Haddad
authors.forename: James S
authors.initials: JS
authors.lastname: Fritz
authors.forename: C
authors.initials: C
authors.lastname: Sarzanini
mesh_terms: D002411:Cation Exchange Resins; D002852:Chromatography, Ion Exchange / Q000379:methods*; D012680:Sensitivity and Specificity
chemical_list: D002411:Cation Exchange Resins