Arabinonic acid, glyceric acid, glycolic acid and formic acid can be determined in organic compounds using ion-exclusion chromatography with subsequent conductivity detection in accordance with inverse suppression. The Metrohm Suppressor Module in its lithium form is used for this purpose: This reduces background conductivity and ensures that the acids are present in their completely disassociated Li+ form. The suppressor is regenerated with lithium chloride.