Hydrophilic Interaction Liquid Chromatography Tandem Mass Spectrometry Methylphosphonic Acid Determination in Water Samples after Derivatization with p-Bromophenacyl Bromide

Abstract

Methylphosphonic acid is the most stable hydrolysis product of organophosphate nerve agents, which persist in environmental samples for a long time. A highly sensitive method of methylphosphonic acid detection in environmental waters has been developed and validated. Derivatization process and stability of p-bromophenacyl bromide methylphosphonic acid derivate were studied. Derivate was stable for 2 days and water content no greater than 7 % did not influence the reaction yield. The analyte concentration step in a rotary evaporator was employed prior to analysis. Detection of the pre-column methylphosphonic acid derivatization product was carried out using tandem mass spectrometry with electrospray ionization after hydrophilic interaction liquid chromatography separation. Evaporation recovery of 90 % was obtained. The intraday and interday repeatability were 6 and 25 %, respectively. Matrix effect influence was not observed. The hydrophilic interaction chromatography method results in excellent peak shape at adequate retention time. Developed approach successfully combines relatively fast derivatization and sample preparation with hydrophilic interaction chromatography and tandem mass spectrometry which allows to achieve the lowest limit of detection (0.1 ng mL−1) for methylphosphonic acid in spiked environmental waters in comparison with other HPLC techniques.