Quality control for Coptidis rhizoma through the determination of five alkaloids by HPLC-ELSD coupled with chemometrics.

A simple, sensitive and reliable high-performance liquid chromatography (HPLC) method with evaporative light scattering detection (ELSD) has been developed for simultaneous determination of five major alkaloids in Coptidis rhizoma. Simultaneous separation of five alkaloids was achieved on a Kromasil C₁₈ analytical column (250 mm x 4.6 mm, 5 µm) with the isocratic elution of acetonitrile : water (30:70, v/v, the pH was adjusted to 6.0 with 0.2 moL L⁻¹ trichloroacetic acid). The drift tube temperature of the ELSD system was set at 115 °C and the nitrogen flow rate was 2.8 L min⁻¹. All the five calibration curves showed a good linear relationship (r² > 0.9991) within the test ranges. The limit of detections and quantifications for the five alkaloids in ELSD were less than 0.88 and 2.73 ng, respectively. The established method was successfully applied to quantify the five ingredients in different C. rhizoma samples and evaluate the internal quality of C. rhizoma samples from various sources by analysing the chemical fingerprints using similarity analysis (SA), hierarchical clustering analysis (HCA) and principal component analysis (PCA), which provided a useful basis of overall evaluation of the quality of C. rhizoma.