Abstract: Four different sample pretreatment procedures, sequential chromatography on Sep-Pak C18 and graphitized carbon columns, ultrafiltration, dialysis and Sephadex-G10 gel column chromatography, were used to purify oligosaccharides to remove lactose from crude extracts. Ion exchange chromatography was used to determine the removal of lactose and the loss of oligosaccharides. The Sephadex-G10 method was shown to be the best of the four methods. Oligosaccharides in goat milk were identified and structurally analyzed by ultra performance liquid chromatography-Q-Exactive Focus tandem mass spectrometry. The total ion current (TIC) chromatogram was recorded, and based on it, the gradient elution program was determined as follows: 0–20 min, 95%–78% A (acetonitrile); 20–35 min, 78%–73% A; 35–38 min, 73%–62% A; 38–45 min, 62%–50% A. A significantly larger number of oligosaccharides were identified in the samples purified by gel filtration chromatography than the crude extract samples. The oligosaccharide isomers in goat milk were separated effectively under the optimal chromatographic conditions. This method could be considered as an important tool for structural analysis of goat milk oligosaccharides.

Key words: goat milk, oligosaccharides, ultra performance liquid chromatography-Q-Exactive Focus tandem mass spectrometry