Single standard substance for the determination of nine volatile components in the distillate of Fructus Gardeniae and Radix Curcumae (an intermediate of Xingnaojing Injection).

Xingnaojing Injection is a traditional Chinese medicine extensively used for stroke and cerebral ischemia. For better in-process quality control of Xingnaojing Injection, a method for the analysis of its intermediate (i.e., the distillate of Fructus Gardeniae and Radix Curcumae) is needed to monitor and optimize the hydrodistillation extraction process. In this work, nine major volatile components in the intermediate were identified: isophorone, 4-methylene-isophorone, curcumenone, curcumenol, curdione, curzerenone, furanodienone, curcumol, and germacrone. A quantitative analysis of multi-component with a single-marker method based on high-performance liquid chromatography with diode array detection was developed for the simultaneous determination of the nine components. In this method, only curdione was needed as the reference substance, and the other eight components were determined using their relative correction factors to curdione. In the method validation, good linearity (r > 0.9999), sensitivity, repeatability, and accuracy (recoveries within 95.3-105.4%) were shown. The repeatability and robustness of the relative correction factors were studied with different column temperatures, flow rates, detection wavelengths, columns, and instruments. In sample analyses, consistent results between the proposed method and the external standard method were shown. The proposed method provides a comprehensive and low-cost tool for the quality assessment of the intermediate of Xingnaojing Injection.