Determination of rhynchophylline and hirsutine in rat plasma by UPLC‐MS/MS after oral administration of Uncaria rhynchophylla extract

An ultra‐performance liquid chromatography with tandem mass spectrometry (UPLC–MS/MS) method was developed and validated to concurrently determine rhynchophylline and hirsutine in rat plasma. The sample preparation of rat plasma was achieved by alkalization and liquid–liquid extraction. The mass transition of precursor ion → product ion pairs were monitored at m/z 385.2 → 160.0 for rhynchophylline, m/z 369.3 → 144.0 for hirsutine and m/z 414.0 → 220.0 for noscapine (internal standard). This method revealed linear relationships from 2.5 to 50 ng/mL (r² > 0.997) for rhynchophylline and from 2.5 to 50 ng/mL (r² > 0.998) for hirsutine. The limit of quantification values for rhynchophylline and hirsutine in rat plasma were both 2.5 ng/mL. Intra‐day and inter‐day precisions were within 10.6% and 12.5%, respectively, for rhynchophylline and hirsutine, and the accuracy (bias) was <10%. Liquid–liquid extraction of rat plasma samples resulted in insignificant matrix effect, and the extraction recoveries were >83.6% for rhynchophylline, 73.4% for hirsutine and 90.7% for the internal standard. This method was applied successfully to a pharmacokinetic study of rhynchophylline and hirsutine in rats after oral administration. Copyright © 2013 John Wiley & Sons, Ltd.     

反相高效液相色谱法测定植物钩藤中钩藤碱含量

反相高效液相色谱法测定植物钩藤中钩藤碱含量;钩藤;钩藤碱;高效液相色谱法     

以离子液体为流动相添加剂高效液相色谱法分离钩藤药材中的钩藤碱和异钩藤碱

以常用流动相添加剂三乙胺作为对照,建立了以离子液体为流动相添加剂,分离钩藤药材中钩藤碱和异钩藤碱的高效液相色谱方法。以分离度及相关色谱参数为指标,选择了离子液体中咪唑阳离子烷基链长度及阴离子的种类。并分别考察了咪唑阳离子烷基链长度、离子液体浓度、流动相pH值和流动相比例对钩藤碱和异钩藤碱分离的影响,初步探讨了离子液体的分离机理。结果显示,咪唑阳离子的烷基链越长,阴离子的离子液体序列越高,分离效果越好,即[HMIM][BF_4]为最优的流动相添加剂。当[HMIM][BF_4]浓度为16 mmol/L,流动相pH值为3.0,甲醇比例为37%时,钩藤碱和异钩藤碱能够实现基线分离,满足样品分离测定的需求。