探讨液相色谱中部分中药生物碱在SCX柱上的色谱分离行为

Analysis of some alkaloids in Chinese traditional medicine using HPLC on microparticulate strong cation-exchange materials

目的 运用HPLC法以微粒SCX色谱柱对中药中的一些亲水性生物碱成分进行分离分析 ,并考察它们在SCX柱上的色谱机制。方法 选用SpherisorbSCX色谱柱。流动相选用不同离子浓度和 pH的磷酸盐溶液 ,分析麻黄碱类时流动相中加入少量乙腈。测定鲜益母草胶囊中的水苏碱 ,使君子药材中的胡芦巴碱 ,半夏露糖浆中的麻黄碱、伪麻黄碱。结果 选择适当的色谱条件 ,以上成分可以分离测定。各成分在SCX柱上除离子交换保留机制外还有其他保留机制。尽管流动相 pH变化可影响测定成分的质子化带电情况 ,但以含盐水溶液为流动相 ,测定物 pKa值无法用于指示流动相pH在何处时其保留因子开始迅速变化 (增加 )。结论 SCX柱可作为C18柱的补充 ,用于测定中药中一些亲水性生物碱成分 ,并可提供这些生物碱类成分的指纹图谱信息。

OBJECTIVE To evaluate sulfonic acid (SCX)-modified silica column in liquid chromatography for the separation of some alkaloids in Chinese traditional medicine. METHOD SCX-modified silica HPLC columns together with phosphate-aqueous eluents was used. The analytes studied were as follows: 1.stachydrine in fresh motherwort herbs capsule, 2. trigonelline in the seed of Quisqualis indica,3.ephedrine and pseudoephedrine in Banxialu syrups, a preparation composed of 9 different TCM including Herba Ephedrae. RESULTS & CONCLUSION SCX-modified silica HPLC column used with aqueous buffer eluents of appropriate pH and ionic strength can give these hydrophilic alkaoids appropriate retentions and good separations. In the eluents system studied, although eluent pH influenced retention(k) via protonation of basic analytes, the pKa of the analytes could not indicated the pH where retention(k) begins to vary dramatically(increase).The underlying retention mechanism appears to be ion-exchange with the SCX moieties, while other contribution to retention also exist especially dominant at higher eluent pH values. As for stachydrine and trigonelline, these analytes that can obtained appropriate retentions on SCX-modified silica column were poorly retained on C18 column even with aqueous buffer eluents. More studies indicated that SCX-modified silica column can be used to give useful chromatographic fingerprints for the analysis of some alkaloids in Chinese traditional medicine.