| The effect of column temperature on the retention behavior of organic acids(aliphatic carboxylic acids and benzenecarboxylic acids) in ion exclusion chromatography with direct conductivity detection was investigated.Chromatographic separations of organic acids were performed on a Shim-pack SCR-102H ion-exclusion column using p-toluenesulfonic acid or sulfuric acid as mobile phase with a flow rate of 1.2 mL/min at various column temperatures from 25 ℃ to 50 ℃.The separations of six common aliphatic carboxylic acids(formic acid,acetic acid,propionic acid,butyric acid,valeric acid and caproic acid)were performed using 0.2 mmol/L p-toluenesulfonic acid as mobile phase.Six kinds of benzenecarboxylic acids(o-phthalic acid,salicylic acid,benzene acetic acid,p-hydroxybenzoic acid,benzoic acid,o-methylbenzoic acid) were eluted and separated using 0.08 mmol/L sulfuric acid as mobile phase.The results indicated that the retention values of organic acids were decreased with the increase of column temperature.However,for each organic acid,the effect degree of temperature is different.That is to say,the variations of retention values for each organic acid are different with the change of temperature.In general,the variations of retention values for strongly retained organic acids are greater than that for weakly retained species.Through the linear regression data,the conclusion that the linearities of the Van’t Hoff plots for organic acids are satisfactory may be derived.By changing the column temperature,the retention value variations of organic acids(especially the strong retain organic acids) can be realized,the peak shapes and separations of organic acids can be improved. |