Rapid detection of Sarin hydrolysis products based on microextraction by packed sorbent combined with Nano-ESI mass spectrometry

Sarin is a nerve agent the use of which prohibited by the Chemical Weapons Convention. Methylphosphonic acid (MPA) and isopropyl methylphosphonic acid (IMPA) are produced when it is hydrolyzed. The detection of MPA and IMPA was an important marker of nerve agent use and contamination. Due to the low volatility and strong polarity of the hydrolysis products, traditional detection methods such as derivatization gas chromatography or liquid chromatography-mass spectrometry were used to detect these compounds. The detection process was complex and time-consuming. Microextraction by Packed Sorbent (MEPS) and Nano Electrospray Ionization (Nano ESI) experimental setup were built. Various parameters, such as the choice of adsorption material, microextraction procedure, and nanoelectrospray ionization, which influence the detection sensitivity, have been optimized. The limit of detection of Sarin hydrolysis products by the MEPS-Nano ESI-MS techniques was 1 ng/mL, and this was equivalent to the sensitivity of GC or LC. The results reveal that the method could be used to rapidly extract and analyze the contaminated water samples without derivatization and chromatographic separation to confirm the pollution of chemical warfare agents in the field.