Determination of short-chain fatty acids in dietary fiber extracts using ion-exclusion chromatography with suppressed conductivity detection

Abstract

A new chromatographic method for the sequential determination of short-chain fatty acids is described. Acetic, propionic and butyric acids were determined in dietary fiber extracts using ion-exclusion chromatography equipped with inverse chemical suppression and conductivity detection. The best optimization of the chromatographic conditions were achieved when a 100 mm × 7.8 mm ion-exclusion column with a solution of 0.5 mmol L −1 sulfuric acid as eluent in a flow rate of 0.6 mL min −1 were employed. The organic acids were sequentially separated in less than 10 min with limits of detection ranging from 1 up to 7.5 μmol L −1 and limits of quantification from 5 up to 25 μmol L −1. The linearity of the analytical response was studied in the range of 0.005–10 mmol L −1 for acetic acid and 0.025–10 mmol L −1 for propionic and butyric acids with coefficients of determination ( R 2) ranging between 0.9985 and 0.9999. The method was tested and proved to be selective, precise, accurate, reproducible and highly sensitive. Finally, the method was applied in the analysis of biological samples.