Infrared detection of the nerve agent Sarin (isopropyl methylphosphonofluoridate) in water using magnesium oxide for preconcentration

Detection of the nerve agent Sarin is: investigated by using diffuse reflec tance infrared spectroscopy,vith magnesium oxide (MgO) as a preconcentratin g medium, Magnesium hydroxide, produced from magnesium oxide and tt ater, i nitially hydrolyzes the Sarin to isopropyl methylphosphonic acid (IMPA). Th e IMPA then reacts with magnesium hydroxide (a slightly soluble product of the addition of MgO to water) to form an insoluble salt, Gas chromatography mass spectrometry (GC-MS) analysis of the Sarin/water solution indicates h ydrolysis of the Sarin after 5 min of addition of the Nantek MgO and within 15 min after addition of the Aldrich MgO. Capillary electrophoresis analys is of the same Sarin/water solution shows that approximately 30% of the IMP A produced by the Nantek MgO hydrolysis of Sarin is not detected in solutio n, while most of the IMPA produced by tile Aldrich MgO is detected, The dif fuse reflectance infrared (IR) spectrum of the IMPA/MgO sample clearly indi cates the presence of IMPA fur both the Nantek MgO and Aldrich MgO samples, Well-resolved hands for methylphosphonic acid (MPA are also evident for th e Nantek MgO/Sarin sample, while less resolved, weaker bands due to MPA are seen for the Aldrich MgO/Sarin sample. These data suggest that a significa nt percentage of the Sarin is hydrolyzed to MPA by using the Nantek MgO. A detection limit of 98 ppb (Aldrich MgO) and 170 ppb (Nantek MgO) Sarin in m ater is calculated on tile basis of the hand heights and signal-to-noise ra tio.