A pretreatment free method for the determination of seven natural products in a high-salt matrix by online guard column extraction coupled with tandem mass spectrometry

Abstract

In vitro cell models are easy, reproducible, and cost-effective tools for tracking drug absorption rates and for elucidating related mechanisms. Traditionally, before introduction into an analysis system, samples crossing an in vitro cell membrane usually undergo complicated processes including precipitation, centrifugation, and even filtering. In the current study, a generic, sensitive and rapid method was developed for the determination of natural products in the matrix of in vitro drug absorption systems (HBSS, Hank's balanced salt solution). A guard RP-C₁₈ column was used to retain the target compounds, while a tandem mass spectrometry system in the multiple reaction monitoring mode was used to specifically detect the target compounds. In addition, a six-way valve was used to connect the LC and MS systems, and to automatically switch the flow directions between the mass spectrometer and the waste. The method was validated by determining the accuracy, precision and sensitivity using seven natural products including (+)-praeruptorin A (dPA), (−)-praeruptorin A (lPA), (+)-praeruptorin B (dPB), (−)-praeruptorin B (lPB) from Peucedani Radix (Chinese name: Qian-hu), morusin (Mo), sanggenon C (SC), and kuwanon G (KG) from Mori Cortex (Chinese name: Sang-Bai-Pi). The developed method is proposed to be applied for in vitro absorption and transport studies.