Methodological contributions towards LC–MS/MS quantification of free VX in plasma: An innovative approach

A novel analytical method has been developed to detect and quantify VX (O-ethyl S-(2(diisopropylamino) ethyl) (methylphosphonothioate)) in plasma using an LC–MS/MS technique. VX detection and quantification in plasma following percutaneous exposure represent a formidable challenge and it is an important part of the ongoing struggle against chemical warfare agents. Liquid–liquid extraction of VX from plasma was performed and it generated a recovery rate of approximately 65% followed by an LC–MS/MS analysis in a 100% organic phase. An Allure biphenyl column (Restek) was tested with detection limit at 0.5 pg/mL (5 μL injected). Initial application was focused on human skin grafted on nude mice as an experimental model with proper adjustments done for very small quantities of plasma.