Field-Amplified Sample Stacking β-Cyclodextrin Modified Capillary Electrophoresis for Quantitative Determination of Diastereomeric Saponins

Abstract

Successful simultaneous diastereomeric separation and sensitive determination of two pairs of triterpenoidal saponins have been achieved by capillary electrophoresis (CE) using β-cyclodextrin (β-CD) as a stereoselective agent to cooperate with borate complexation. A usual technique for isolation and group separation of saponins was developed as an appropriate purification step prior to the determination of individual saponins by CE. Soyasaponin I ( S1: ), azukisaponin V ( S2: ), bersimoside I ( S3: ) and bersimoside II ( S4: ) could be well separated within 14 min in a fused-silica capillary (60 cm long to the detector with an additional 10 cm to the cathode; 75 µm i.d.). The background electrolyte was borate buffer (80 mM, pH 10), containing 24 mM β-CD. The separation voltage was 14 kV with a detection wavelength of 195 nm. The sample was electrokinetically injected using a voltage of 16 kV for 12 s. Methanol (70%) was used as the diluent for field-amplified sample stacking after hydrodynamic injection of short water plug (5 cm, 4 s). The method was partially validated for linearity, repeatability, reproducibility, limits of detection and limits of quantification. The correlation coefficients of the calibration curves were all >0.998, and the recoveries were from 98.23 to 96.21%.

Techniques for the analysis of pentacyclic triterpenoids in medicinal plants

“…However, despite its advantages, CE cannot discriminate those compounds with close charge‐to‐mass ratios. Therefore, cyclodextrins, surfactants, and organic solvents are often added to enhance the separation capability in its actual application .…”

Capillary electrophoresis in phytochemical analysis (2014–2017)

“…On‐line pre‐concentration techniques, mainly include sample stacking, dynamic pH junction, sweeping, and transient isotachophoresis (tITP), had been frequently used for enrichment of analytes in CE analysis to improve detection limits. For example, field‐amplified sample stacking (FASS) was used for on‐line pre‐concentration of diastereomeric saponins including soyasaponin I, azukisaponin V, bersimoside I and bersimoside II with about 20‐fold sensitive enhancement . Determination of rutin, hyperoside and chlorogenic acid in Flos Farfarae with 14‐, 26‐, and 5‐fold enrichment were achieved by large volume sample stacking (LVSS), respectively .…”

The Role of Cyclodextrins in the Design and Development of Triterpene-Based Therapeutic Agents

“…This method exhibits a series of advantages that support its wide use, such as time effectiveness, low solvent consumption and high-resolution separation even for stereoisomers [ 111 ]. Using the CE method, the simultaneous separation of two pairs of diastereomers triterpenic saponins from Trifolium alexandrinum , namely soyasaponin I, azukisaponin V, bersimoside I and bersimoside II, was achieved by using a dual mechanism that involves the addition of β-CD to the borate buffer solution [ 112 ]; saponins were included in the CD cavity, thus achieving a very effective separation characterized by high resolution, repeatability and detection limits.…”