Simultaneous determination of monosaccharides, disaccharides and fructo-oligosaccharides in milk powder by ultra-filtration clean up coupled with high performance liquid chromatography

Objective To establish a simple and rapid method based on ultra-filtration clean up method and high performance liquid chromatography(HPLC) to determine 7 kinds of carbohydrate compounds(fructose, glucose, sucrose, lactose, kestose, nystose and 1F-fructofuranosylnystose) in milk powder. Methods Milk powder sample was dissolved by water, and then treated with ultra-filtration centrifugal molecular weight cut-off 3000 tube to remove protein, nucleic acid and polysaccharide macromolecular substances by high-speed centrifugation. The separation was performed on a Luna NH2 column with isocratic elution of acetonitrile: water(75:25, v:v)as the mobile phase. The analytes were determined by a refractive index detector(RID). Results Under the optimal conditions, the calibration curves were linear in the range of 0.15 to 10.0 mg/m L with correlation coefficients larger than 0.999. The limits of detection(LODs) were from 0.039 to 0.087 g/100 g. The mean recoveries for milk powder sample at three spiked concentration levels of 0.50~2.0 g/100 g were in the range of 81.2% to 105%, and the relative standard deviations(RSD) ranged from 1.1% to 6.2%(n=6). Conclusion This method is simple, rapid, and it is suitable for the identification and quantification of monosaccharides, disaccharides and fructo-oligosaccharides in milk powder.