PNNL

Abstract

A direct an anion exchange, ion chromatography (IC)-based method for the detection of the chemical warfare agent surrogate O-isopropyl methylphosphonic acid (IMPA) in agar medium has been developed. This is the first report of the systematic development and validation of an IC-based method for the analysis of the chemical warfare agent degradation product, IMPA, in Petri dishes containing the agar medium with 10, 100 and 1000 mg/mL IMPA. Samples were prepared by dilution of the agar medium with deionized water followed by sonication and then filtration before the analysis by IC/conductivity detection. Using this method, the amount of IMPA in the Petri dishes was measured. Excellent separation efficiency and freedom from interference due to common anions such as phosphate and sulfate was obtained in the developed methods. Retention time precision is less than 1.0 % relative standard deviation (%RSD) and the detection limit is 0.1 mg/mL. Three calibration curves were performed over the range 1-100 mg/mL using blank agar matrices spiked with five IMPA concentrations; with correlation coefficients (R^2) of 0.993, 0.991, and 0.992 for the calibration standard without dilution of agar matrix, at 4-times dilution and at 40-times dilution, respectively. Using three different samples at three IMPA spike levels, analysis accuracy was assessed by spiking the actual agar samples with IMPA. Average recoveries were 76, 79, and 84% for 10, 100, and 1000 mg/mL, respectively.