title: Qualitative analysis of some carboxylic acids by ion-exclusion chromatography with atmospheric pressure chemical ionization mass spectrometric detection.
abstract: A simple, selective and sensitive method for the determination of carboxylic acids has been developed. A mixture of formic, acetic, propionic, valeric, isovaleric, isobutyric, and isocaproic acids has been separated on a polymethacrylate-based weak acidic cation-exchange resin (TSK gel OA pak-A) based on an ion-exclusion chromatographic mechanism with detection using UV-photodiode array, conductivity and atmospheric pressure chemical ionization mass spectrometry (APCI-MS). A mobile phase consisting of 0.85 mM benzoic acid in 10% aqueous methanol (pH 3.89) was used to separate the above carboxylic acids in about 40 min. For LC-MS, the APCI interface was used in the negative ionization mode. Linear plots of peak area versus concentration were obtained over the range 1-30 mM (r2=0.9982) and 1-30 mM (r2=0.9958) for conductimetric and MS detection, respectively. The detection limits of the target carboxylic acids calculated at S/N=3 ranged from 0.078 to 2.3 microM for conductimetric and photometric detection and from 0.66 to 3.82 microM for ion-exclusion chromatography-APCI-MS. The reproducibility of retention times was 0.12-0.16% relative standard deviation for ion-exclusion chromatography and 1.21-2.5% for ion-exclusion chromatography-APCI-MS. The method was applied to the determination of carboxylic acids in red wine, white wine, apple vinegar, and Japanese rice wine.
authors.affiliation: National Institute of Advanced Industrial Science and Technology at Seto, Aichi, Japan. murad.helaleh@lycos.com
authors.forename: Murad I H
authors.initials: MI
authors.lastname: Helale
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Tanaka
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Taoda
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: D001274:Atmospheric Pressure; D002264:Carboxylic Acids / Q000032:analysis*; D002852:Chromatography, Ion Exchange / Q000379:methods*; D004563:Electrochemistry; D013058:Mass Spectrometry / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D002264:Carboxylic Acids