对纯化的新型细菌多糖进行酸水解,用乙硫醇-三氟乙酸和醋酐-吡啶体系先后对酸水解物进行衍生,与之前报道不同的是糖醛酸得到有效衍生化.以木糖为内标,采用气相色谱-质谱联用(GC-MS)定量分析该多糖酸水解物中单糖和糖醛酸衍生物发现,该多糖的糖链由岩藻糖、葡萄糖、葡萄糖醛酸和半乳糖组成,其相对物质的量比为1.50∶1.0∶0.79∶2.06;中性糖比例与糖醇乙酸酯化分析岩藻糖、葡萄糖和半乳糖的相对物质的量比(1.76∶1.0∶1.98)接近；糖醛酸咔唑法与该方法分析葡萄糖醛酸的含量分别为16.19％和14.85％.以上结果表明所建立的衍生化方法及GC-MS同时定量分析多糖酸水解物中单糖和糖醛酸的方法可行.此外还对葡萄糖醛酸的质谱裂解机理进行了阐述.%The purified novel bacterial polysaccharide was acid-hydrolyzed, followed by the subsequent derivatization using ethanethiol-trifluoroacetic acid and acetic anhydride-pyridine systems sequentially. Our findings differ from the previous reports in that the glucuronic acid was obtained through effective derivatization. The neutral sugars and glucuronic acid were analyzed using gas chromatography-mass spectrometry (GC-MS) with xylose as an internal standard. The polysaccharide was found to be composed of fucose, glucose, glucuronic acid and galactose, with the relative molar ratio of 1. 50: 1. 0: 0. 79= 2. 06. The neutral sugars ratio was similar to the relative molar ratio for fucose, glucose and galactose of 1. 76: l. 0: 1. 98 through alditol acetates determined by GC. The percentages of glucuronic acid analyzed using either the carbazole and sulfuric acid method or the above method were 16. 19% and 14. 85%, respectively. These results indicate that it is practicable to use the derivatization method and GC-MS to quantitatively analyze neutral sugars and glucuronic acid simultaneously in polysaccharide. For GC-MS analysis, the procedure was developed for the simultaneous determination of the derivatives in 25 min, and was performed using an HP-5MS column. Molecular ion peaks were observed in the electron ionization ( E1) mass spectra. The fragmentation mechanism for glucuronic acid derivative is discussed in detail.
展开▼
