[High sensitive non-derivative determination of cyclovirobuxin D by high-performance liquid...

A high-performance liquid chromatography-electrochemical detection (HPLC-ECD) method was developed to determine cyclovirobuxin D (CVB-D) levels in tablets and human blood samples. A column with a positive charge-modified C18 stationary phase, C18HCE, was selected to analyze CVB-D, because it provided a sharper and more symmetric peak for CVB-D than conventional C18 stationary phase. Two types of working electrode materials, glassy carbon (GC) and boron-doped diamond (BDD), were evaluated. BDD was found to provide better sensitivity than GC owing to its lower background current and baseline noise. Utilizing the BDD electrode, C18HCE column, and optimized mobile phase composition, the developed HPLC-ECD method showed a much better sensitivity. The limit of detection and limit of quantification of the HPLC-ECD method for CVB-D were 0.198 and 0.297 μg/L, respectively. It was approximately 12727, 11481, and 2630 times more sensitive than ultraviolet (UV), evaporative light scattering detection, and charged aerosol detection, respectively. The sensitivity of the developed HPLC-ECD method was comparable or even better (16.8 times) than reported mass spectrometry (MS) methods for the determination of CVB-D. Additionally, it offered a much wider linear dynamic range (up to 4 orders of magnitude, 0.297-1891 μg/L) and was much less complicated than MS methods for determination of CVB-D. The developed HPLC-ECD method can be used for determination of CVB-D at both high and low concentrations. Good intra-day (relative standard deviation (RSD) of peak area<5.08%) and inter-day (RSD of peak area<5.57%) reproducibilities of the developed HPLC-ECD method were obtained even for a low mass concentration (59.1 μg/L) sample. After the optimized parameters were acquired, this method was applied to the quantitative analysis of CVB-D in CVB-D tablets and human blood samples. With a slight modification, the current HPLC-ECD method can also be applied to analyze many other basic compounds including basic drugs and environmental pollutants.