CIRCLE CELL® FT-IR Analysis of Chemical Warfare Agents in Aqueous Solutions

Abstract

The qualitative and quantitative FT-IR analyses of dilute aqueous solutions of the chemical warfare threat agents tabun (GA), sarin (GB), and soman (GD) were evaluated with the use of the CIRCLE CELL®. Infrared spectra were recorded with a Nicolet 60SXB FT-IR spectrometer fitted with a liquid-nitrogen-cooled MCT-A detector. The CIRCLE CELL® used a modified micro, high-pressure, flow-through sampling accessory fitted with a ZnSe internal reflection element. Peak heights were evaluated with the Nicolet SUPER QUANT program after spectral subtraction of the solvent. The P=O stretching absorption band, centered around 1240 cm−1, produced good quantification in the concentration range 0.5 to 2.0 mg/mL. In this concentration range the intra-daily precision had a percent coefficient of variation (% CV) of less than 3.0%, while the inter-daily precision yielded a % CV of less than 6.0%. The detection limit was observed to be 0.3 mg/mL for GA and 0.2 mg/mL for GB and GD.