In this study, we used quantitative high-performance liquid chromatography equipped with an ultraviolet detector (HPLC-UV) and solid phase extraction (SPE) to determine the levels of four phenylethanoid glycosides and five triterpene acids in Liuwei Dihuang capsules (LDCs). LDCs were methanol-extracted and purified using a 500 mg/6 mL silica-based C18 SPE cartridge. Two elutions were analyzed on a ChromCore C18 column under two HPLC conditions. To improve the pretreatment clean-up, an array of silica- and polymer-based SPE cartridges were compared. Both wash and elution steps were also optimized to achieve the highest removal of impurities. Under optimal chromatographic conditions, good linearity was achieved for all compounds (correlation coefficient of r ≥ 0.999), with a quantification limit ranging from 0.0076 to 0.418 μg/mL. The method had satisfactory efficiency and reproducibility with recovery rates ranging from 91.6 to 99.3% with a relative standard deviation below 1.5%. Taken together, this demonstrated SPE as a suitable extension of HPLC-UV for the determination of phenylethanoid glycosides and triterpene acids in complex LDCs.

中文翻译：

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固相萃取-HPLC-UV法测定六味地黄胶囊中四种苯乙醛糖苷和五种三萜酸的含量

在这项研究中，我们使用配备了紫外检测器（HPLC-UV）和固相萃取（SPE）的定量高效液相色谱法测定六味地黄胶囊（LDCs）中四种苯乙醛糖苷和五种三萜酸的含量。用甲醇萃取最不发达国家，并使用500 mg / 6 mL二氧化硅基C18 SPE柱纯化。在两个HPLC条件下，在ChromCore C18色谱柱上分析了两种洗脱液。为了改善预处理的净化效果，对一系列基于硅胶和聚合物的SPE柱进行了比较。还优化了洗涤和洗脱步骤，以实现最高的杂质去除率。在最佳色谱条件下，所有化合物均具有良好的线性（相关系数r≥0.999），定量限为0.0076至0.418μg/ mL。该方法具有令人满意的效率和可重复性，回收率在91.6％至99.3％之间，相对标准偏差低于1.5％。综上所述，这证明了SPE作为HPLC-UV的合适扩展，可用于测定复杂LDC中的苯乙醛糖苷和三萜酸。