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9.MS 的应用:通常用电子轰击型质谱法(EI-MS),以皂甙的乙酰化物、三甲基硅醚化物或甲醚化物等挥发性高的衍生物进行测定。由糖的碎片离子(如图5)可得到末端糖、低聚糖连接顺序的主要信息。但乙醚化物更容易获得,而 TMSi 化物因碎片离子的质量较大,使低聚糖离子的解析带来困难。MS 法可控制纯度,如在 Rb_1中混有 Rb_2,在其乙酰化物质谱中,由末端阿拉伯糖的碎片 m/e 259可断定。基峰常为糖的碎片离子或乙酰基离子。
9. Application of MS: It is usually determined by electron bombardment mass spectrometry (EI-MS) using a highly volatile derivative such as saponin acetylate, trimethylsilyletherate, or methyl etherate. From the fragment ions of sugar (Figure 5), the main information of the terminal sugar and oligosaccharide connection sequence can be obtained. However, the ether compound is more easily obtained, while the TMSi compound has a relatively large mass of fragment ions, making it difficult to resolve the oligosaccharide ions. The MS method controls the purity. For example, Rb_1 is mixed with Rb_2. In its acetylate mass spectrum, it can be determined from the end arabinose fragment m/e 259. The base peak is often a fragment or acetyl ion of sugar.