title: Vacancy ion-exclusion chromatography of haloacetic acids on a weakly acidic cation-exchange resin.
abstract: A new and simple approach is described for the determination of the haloacetic acids (such as mono-, di- and trichloroacetic acids) usually found in drinking water as chlorination by-products after disinfection processes and acetic acid. The new approach, termed vacancy ion-exclusion chromatography, is based on an ion-exclusion mechanism but using the sample solution as the mobile phase, pure water as the injected sample, and a weakly acidic cation-exchange resin column (TSKgel OApak-A) as the stationary phase. The addition of sulfuric acid to the mobile phase results in highly sensitive conductivity detection with sharp and well-shaped peaks, leading to excellent and efficient separations. The elution order was sulfuric acid, dichloroacetic acid, monochloroacetic acid, trichloroacetic acid, and acetic acid. The separation of these acids depends on their pKa values. Acids with lower pKa values were eluted earlier than those with higher pKa, except for trichloroacetic acid due to a hydrophobic-adsorption effect occurring as a side-effect of vacancy ion-exclusion chromatography. The detection limits of these acids in the present study with conductivity detection were 3.4 microM for monochloroacetic acid, 0.86 microM for dichloroacetic acid and 0.15 microM for trichloroacetic acid.
authors.affiliation: National Institute of Advanced Industrial Science and Technology, 110 Nishiibara-cho, Seto, Aichi 489-0884, Japan. murad.helaleh@lycos.com
authors.forename: Murad I H
authors.initials: MI
authors.lastname: Helaleh
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Tanaka
authors.forename: Masanobu
authors.initials: M
authors.lastname: Mori
authors.forename: Qun
authors.initials: Q
authors.lastname: Xu
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Taoda
authors.forename: Ming-Yu
authors.initials: MY
authors.lastname: Ding
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
mesh_terms: D000085:Acetates / Q000032:analysis* / Q000302:isolation & purification; D019342:Acetic Acid; D002411:Cation Exchange Resins; D002852:Chromatography, Ion Exchange / Q000379:methods*; D003999:Dichloroacetic Acid / Q000032:analysis; D004553:Electric Conductivity; D006863:Hydrogen-Ion Concentration; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012997:Solvents; D013464:Sulfuric Acids; D014238:Trichloroacetic Acid / Q000032:analysis; D014867:Water / Q000032:analysis
chemical_list: D000085:Acetates; D002411:Cation Exchange Resins; D012997:Solvents; D013464:Sulfuric Acids; D014867:Water; C006972:chloroacetic acid; D014238:Trichloroacetic Acid; D003999:Dichloroacetic Acid; C033158:sulfuric acid; D019342:Acetic Acid