High-performance liquid chromatography determination of triptolide in vitro permeation studies

A simple, rapid and sensitive high-performance liquid chromatography (HPLC) method has been developed for the determination of triptolide. Triptolide was separated from skin endogenous and blank matrices on a 5 μm LiChrospher RP-C₁₈ column by a mobile phase of methanol-water (65:35, v/v). The permeation samples were injected directly without pretreatment. The limit of quantitation (LOQ) and detection (LOD) for triptolide in permeation samples were far below (0.01 and 0.005 μg/mL, respectively). The method was linear over the range of 0.1-104.2 μg/mL with r² = 0.9999. This HPLC assay is promising for measuring in vitro percutaneous penetration of triptolide through mice skins and also can be performed in the triptolide-loaded microemulsions formulation screening.