LC-electrolyte switch in a contiguous time segments to analyze multi-components: Simultaneous determination of phenolic acids and iridoids in rat plasma after inhalation administration of Reduning aerosol.

The optimization of electrolytes, kinds and concentrations, in mobile phase for multiple constituents analyzing using high-performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI-MS) was usually compromised to ensure good LC separation of partial components. However, the compromised electrolytes could lead to ionization suppression of some of the analytes. To solve the compromise of electrolytes within various components, taking phenolic acids and iridoids as a case, we used electrolyte switch in contiguous running time segments of UPLC-ESI-MS/MS to ensure chromatographic separation of chlorogenic acid, neochlorogenic acid and cryptochlorogenic acid and improve the response of geniposide. Then the method was applied for pharmacokinetic study of the four components in rat after inhaling Reduning aerosol for the first time. The complete separation of the three chlorogenic acid isomers was achieved and the LLOQs of neochlorogenic acid, chlorogenic acid, cryptochlorogenic acid, and geniposide were 1, 1, 3, and 0.2 ng/mL, respectively. In conclusion, we developed a sensitive and time-saving LC-MS/MS method for the quantitative analysis of chlorogenic acid, neochlorogenic acid, cryptochlorogenic acid, and geniposide in rat plasma, and this method appears to be useful for pharmacokinetic studies of Reduning aerosol. The method provided a sight to alleviate compromise of electrolytes in mobile phase for HPLC-ESI-MS in analyzing multi-components.