Determination of carboxylic acids by ion-exclusion chromatography with non-suppressed conductivity and optical detectors

Summary Determination of carboxylic acids using non-suppressed conductivity and UV detections is described. The background conductance of 1-octanesulfonic acid, hexane sulfonic acid and sulfuric acid at varying concentrations was determined. Using 0.2 mM 1-octanesulfonic acid as a mobile phase and an injection volume of 300 l, the detection limits range from 1 M for formic acid to 10 M for butyric acid. The conductivity detector was connected in tandem with a Waters 484 optical detector at 210 nm, which allowed the analysis of carboxylic acids from 0.01 mM to 10 mM. The dependence of the retention of carboxylic acids on the eluent pH is discussed.