Simultaneous determination of multiple platycosides with a single reference standard in Platycodi Radix by high-performance liquid chromatography coupled with evaporative light scattering detection.

ABSTRACT

A traditional external standard method using HPLC coupled with evaporative light scattering detection has been developed for fast and accurate determination of seven platycosides in Platycodi Radix. However, inevitable difficulties in reference standards preparation process, which are quite costly and time consuming, have made its application limited. To avoid this inconvenience, a simultaneous determination of multiple components with a single reference standard strategy, which could be realized by calibrating the standard curve with internal standard and response factors, was introduced to the HPLC coupled with evaporative light scattering detection method. This is the first time that an incorporation of these two methods has been realized. Among seven ingredients, platycodin D was selected as the internal standard for its relatively easy preparation and low cost. Moreover, according to the investigation on concentration-dependent effects over response factors and robustness test, platycoside E, deapioplatycodin D, platycodin D, and polygalacin D2 were chosen to be the indicators for this novel method. The present method has not shown statistically significant differences with a traditional external standard method as verified sample analysis by the F-test (p = 95%, n = 6).