薄层色谱结合气相色谱-质谱法评价几种市售功能糖质量

目的：建立基于薄层色谱（TLC）结合气相色谱-质谱（GC-MS）法评价市售功能糖质量。方法：首先应用TLC结合苯胺-二苯胺显色对功能糖样品进行初步鉴定，然后应用甲基化反应结合GC-MS分析，确定其糖苷键类型及其比例。TLC展开剂为正丁醇-异丙醇-水-醋酸（7：5：2：1）；用于糖苷键分析的毛细管色谱柱为HP-5MS（30 m×0.25 mm×0.25 μm），进样量1 μL，程序升温条件为起始温度120℃，以5℃·min^-1升温至200℃，以8℃·min^-1升温至250℃，以20℃·min^-1升至280℃。结果：乳果糖样品TLC呈单一条带且显红色，但其不含t-Galp，说明样品与标示不符。大豆低聚糖样品TLC条带颜色及糖苷键分析结果与蔗糖和棉子糖系列寡糖相近，说明产品中可能含有蔗糖、棉子糖、水苏糖等。海藻糖样品TLC显色较弱，仅含有t-Glcp，说明产品可能含有海藻糖但糖含量较低。低聚果糖样品部分条带显红色，与低聚果糖特征一致；但t-Glcp含量较高，说明还含有低聚葡萄糖成分。低聚木糖条带颜色明显不同于对照品，且样品中未检出与木糖相关糖苷键，提示特征与标示产品不符。结论：检测的市售乳果糖和低聚木糖样品与标示不符，存在明显质量问题，低聚果糖中可能混有低聚葡萄糖。

Objective:To establish an effective method,based on TLC and GC-MS,for quality evaluation of commercial functional saccharides. Methods:TLC was used to separate saccharides and colorized with aniline-diphenylamine agent for preliminary identification. Methylation combined with GC-MS analysis was employed to analyze the glycosidic linkages. TLC developing solvent was 1-butanol-isopropanol-water-acetic acid(7:5:2:1). Capillary column for glycosidic linkages analysis was HP-5MS (30 m×0.25 mm×0.25 μm) and the injection volume was 1 μL. The column temperature was set at 120 and then programmed at 5℃·min^-1 to 200℃,then at 8℃·min^-1 to 250℃,and finally,at 20℃·min^-1 to 280℃. Results:A single red band was detected in TLC chromatogram of lactulose sample but t-Galp was not found. This indicated that the sample was not in accordance with its claimed characters. The TLC band and glycosidic linkage of soybean oligosaccharides were similar with those of sucrose and raffinose family oligosaccharides,which indicated that the sample might contain sucrose,raffinose and stachyose. TLC band of trehalose was not obvious with only t-Glcp being detected,which was in accordance with the characters of trehalose,but the content of saccharides was low. High ratio of t-Glcp was detected in fructo-oligosaccharides,indicating that glucose-oligosaccharides also existed in this sample. The band color of xylo-oligosaccharides sample was significantly different from the reference and no xylose type linkages were detected,which suggested the sample was not in accordance with the claimed characters. Conclusion:Investigation results of lactulose,fructo-oligosaccharides and xylo-oligosaccharides samples did not conformed to their claimed characters,indicating obvious quality defect. And glucose-oligosaccharides might exist in fructo-oligosaccharides samples.