Trace Level Analysis of Sarin and VX in Food Using Normal Phase Silica Gel and Ultra-Performance Liquid Chromatography–Time-of-Flight Mass Spectrometry (UPLC–TOF–MS)

Ultra-Performance Liquid Chromatography/electrospray ionization mass spectrometry was used for the trace level determination of isopropyl methylphosphonofluoridate (Sarin, GB) and (O-ethyl S-[2-(diisopropylamino)­ethyl] methylphosphonothioate (VX) after extraction from various foods. A method utilizing normal phase silica gel was developed for the sample preparation and extraction of VX and GB from food. The extraction efficiencies of the normal phase silica gel method for VX was compared to those of other commercial solid phase extraction media and was found to be comparable. Sarin was found to be incompatible with both the mixed mode cation exchange (MCX) sorbents and QuEChERS methods that are commercially available but was successful with the normal phase silica gel method. The linear range of quantitation for VX was 0.1–330 ng/mL and for GB was 20–1200 ng/mL. The average recoveries of VX and GB from the various food matrices along with the corresponding relative standard deviations (RSDs) are reported.