Peak purity was studied by diode-array detector in high performance liquid chromatography (DAD-HPLC) to assay seven Chinese medicinal standards which were prepared of various different concentrations. Three injections were executed for each concentration sample, then the SI values were obtained by comparing the absorption spectra of three injections of each concentration's value. The results showed that SI values increased when the concentrations decreased. The absorption spectra of peaks of reference standards and samples are usually not matched while running a gradient system, because the background of the solvent is continuously changed. However, a good match was obtained by subtracting absorption spectrum of baseline before comparing absorption spectra of reference standards and analytical peaks. The effect of insufficient running time for HPLC analysis was also studied. For example, Ching-Shy-Huah-Tarn - Tang normally had a running time of 60 min. If the running time was changed from 60 min to 20 min, the peak area was significantly interfered by the previous run during a continuous eight injections trial.
Ku, C.-C.; Chung, Y.-S.; and Ku, H.
"The study of peak purity of Chinese medicinal compositions by HPLC/DAD,"
Journal of Food and Drug Analysis: Vol. 2
, Article 2.
Available at: https://doi.org/10.38212/2224-6614.3020