Application of isoabsorption plots generated by high-performance liquid chromatography with diode array detection to the development of multicomponent quantitative analysis of traditional herbal medicines

Multicomponent quantitative analysis is one of the mainstream quality control methods of traditional herbal medicines. Since the constituents of traditional herbal medicines samples are complex, the development of high‐performance liquid chromatography methods is laborious. In this study, an isoabsorption plot, a chromatographic/spectrometric data image plotted by diode array detection was utilized to facilitate the establishment of a high‐performance liquid chromatography method by optimizing and validating the detection conditions off‐line. Consequently a simple, reliable and accurate method for simultaneous determination of seven active polyphenolic components (protocatechuic acid, chlorogenic acid, caffeic acid, p‐coumaric acid, rosmarinic acid, scutellarin, and apigenin) in Qingfei mixture, a long‐used Chinese prescription, was developed. The chromatographic separation was performed on a C18 column with gradient elution of phosphoric acid aqueous solution (0.05%, v/v) and acetonitrile, and a wavelength switch program optimized with isoplot was adopted for detection. The method was validated in terms of linearity, sensitivity, precision, repeatability, and accuracy and was successfully applied to the simultaneous determination of the seven polyphenolic components in different production batches of Qingfei Mixture. These results indicated that isoplot is an effective tool to improve the establishment of multicomponent quantitative analysis methods.