Analysis of carbohydrates in drinks by high-performance liquid chromatography with a dynamically modified amino column and evaporative light scattering detection

A high-performance liquid chromatographic method with a dynamically modified amino column and evaporative light-scattering detector (ELSD) was established for the direct analysis of the carbohydrates in some drinks. A separation column (Zorbax Rx-SIL, 250 mm×4.6 mm I.D., 5 μm, Hewlett-Packard, USA) which was modified by ethylenediamine and a guard column (Zorbax Rx-SIL, 12.5 mm×4.6 mm I.D., 5 μm) were used. The mobile phase was a mixture of water–acetonitrile (1:2.6, v/v) containing 0.03% (v/v) ethylenediamine. Regression equations revealed linear relationship (correlation coefficients=0.996–0.999) between the mass of carbohydrates injected and the carbohydrates peak areas detected by ELSD. The detection limits of ELSD (S/N=3) were between 0.2 and 1.2 μg for different carbohydrates. This method is simple and sensitive.