Simultaneous determination of aliphatic and aromatic acids in plant tissue extracts by ion-exclusion chromatography

Abstract

Ion-exclusion chromatography (IEC) is commonly used for the separation of carboxylic acids. In contrast, there are a few applications of the IEC in the separation of aromatic acids based on hydrophobic interaction between solute and resin. The simultaneous separation of aliphatic and aromatic acids by IEC in a sulfuric acid/acetonitrile eluent using a polystyrene–divinylbenzene column (Aminex HPX-87H) followed by UV detection at 200 nm is described. The effects of the concentrations of sulfuric acid and acetonitrile in the eluent, as well as of column temperatures on the retention of the test acids has been investigated. Separation of eight aliphatic and nine aromatic acids was satisfactory using a 5 mM H 2SO 4 and 7.5% acetonitrile eluent at 50°C. Detector response was linear in the range 1×10 −3–1 mM. The proposed methods were demonstrated using direct injection of the sample for the determination of carboxylic and aromatic acids in plant tissue extracts.