Quality by design‐based capillary electrophoresis method development for the quantitative analysis of four iridoid compounds in Gentiana macrophylla Radix

Abstract

In this study, the capillary electrophoresis‐photodiode array detector was employed for the analysis of four iridoid compounds in Gentiana macrophylla Radix (RGM), and the method was optimized based on the concept of analytical quality by design (AQbD). The peak areas relative standard deviation (n = 3) and resolution of the four analytes were selected as critical method attributes. Fractional factorial design test combined with Pareto analysis were employed to screen critical method parameters (buffer concentration, pH, sodium dodecyl sulfate [SDS] micelle concentration, temperature, and voltage). Subsequently, three main factors (buffer concentration, buffer pH, and SDS concentration) were selected by central composite design test for constructing the design space. The optimal separation conditions as follows: capillary column (50.2 cm × 50 µm, detection length 40 cm). Working background electrolyte consisted of 51 mmol/L borax solution (pH = 9.47) and 40 mmol/L SDS. The samples were injected by pressure (5 s at 0.5 psi) and the detection was performed at 254 nm. Applied voltage was 20 kV and column temperature was 23°C. The developed method is rapid and reliable for the quantitative analysis of four iridoid compounds in RGM, providing a reference for the application of AQbD concept in the analysis of natural products.

Holistic quality evaluation method of Epimedii Folium based on NIR spectroscopy and chemometrics

“…Similarity analysis methods were used to evaluate model performance. The cosine value 12 and Pearson correlation coefficient 22 are commonly used to evaluate the similarity between fingerprints. The closer their values are to 1, the higher the similarity between the two fingerprints.…”

“…11 The traditional method to improve the interpretability of (Y) and NIR spectral data are used as the independent variable (X). 12 Compared to the mid-infrared spectrum, characteristic absorption related to compounds cannot be seen in the NIR spectra, and this strategy can enhance the interpretability of NIR spectra. In addition, HPLC fingerprints that reveal the overall quality of traditional Chinese medicines are obtained in a short period of time, and the use of organic reagents is avoided.…”

“…The NIR spectrum is combined with a partial least squares regression (PLSR) model to predict the absorbance values at each retention time point of the HPLC fingerprint to obtain the predicted HPLC fingerprint. Unlike quantitative models, in which the contents of various indicators in Epimedii Folium are used as the predicted values (Y), in the fingerprint conversion process the absorbance values at each retention time point of the HPLC fingerprint are used as the predicted values (Y) and NIR spectral data are used as the independent variable (X) 12 . Compared to the mid‐infrared spectrum, characteristic absorption related to compounds cannot be seen in the NIR spectra, and this strategy can enhance the interpretability of NIR spectra.…”