Application of zirconium-modified silica gel as a stationary phase in the ion-exclusion chromatography of carboxylic acids. II. Separation of aliphatic carboxylic acids with pyromellitic acid as eluent and with suppressed conductimetric detection.

K Ohta

Index: J. Chromatogr. A. 920(1-2) , 181-91, (2001)

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Abstract

The application of zirconium-modified silica gels (Zr-Silica) as stationary phases for ion-exclusion chromatography with conductimetric detection (IEC-CD) for C1-C8 aliphatic carboxylic acids (formic, acetic, propionic, butyric, valeric, caproic, heptanoic and caprylic acids) was carried out using pyromellitic acid as the eluent. Zr-Silicas were prepared by the reaction of the silanol group on the surface of silica gel with zirconium tetrabutoxide [Zr(OCH2CH2CH2CH3)4] in ethanol solution. An ASRS-Ultra anion self-regenerating suppressor in the K+ form was used for the enhancement of conductimetric detector response of these aliphatic carboxylic acids. A Zr-Silica adsorbed on 10 mg zirconium g(-1) silica gel was the most suitable stationary phase in IEC-CD for the separation of these aliphatic carboxylic acids. Excellent simultaneous separation and highly sensitive detection for these aliphatic carboxylic acids were achieved in 25 min by IEC-CD with the Zr-Silica column (250x4.6 mm I.D.) and a 0.2 mM pyromellitic acid containing 0.15% heptanol as the eluent.