Determination of xylo-oligosaccharides in health foods by high performance liquid chromatography with refractive index

  Objective  To develop a method for the determination of xylo-oligosaccharides (in xylose) in health foods by high performance liquid chromatography with refractive index (HPLC-RI).

  Methods  The samples were extracted with water for 30 minutes then higher molecular saccharides were precipitated with alcohol at low temperature. After subsequently hydrolyzed with sulfuric acid solution for 90 minutes, neutralized with sodium hydroxide solution and separated on a NH₂ column, the samples were detected quantitatively with refractive index detector using external standard. The xylo-oligosaccharides content was measured based on the difference value for xylose concentration before and after the hydrolysis process.

  Results  A high linearity of the calibration curve between the peak area and the mass concentration of xylose was observed (Y = 61 349.49X – 1 028.52, r = 0.999 9) under the xylose concentration ranging between 0.25 – 5.00 mg/mL. The recovery rates were between 83.5% and 96.7% and the relative standard deviations ranged from 1.67% to 4.82% in health foods. The detection limit of the method is 1.1 g/kg and the quantification limit is 3.3 g/kg.

  Conclusion  The established method is accurate, sensitive, and simple and could be used for the determination of xylo-oligosaccharides in health foods.