Solid phase microextraction sampling and gas chromatography/mass spectrometry for field detection of the chemical warfare agent O‐ethyl S‐(2‐diisopropylaminoethyl) methylphosphonothiolate (VX)

Abstract

Solid phase microextraction sampling and gas chromatography/mass spectrometry for field detection of the chemical warfare agent O-ethyl S-(2-diisopropylaminoethyl) methylphosphonothiolate (VX)A rapid detection method for the chemical warfare nerve agent VX was developed using SPME and gas chromatography/mass spectrometry (GC/MS). Five commercially available SPME fiber coatings were evaluated to determine the optimal fiber coating and conditions for extraction. The use of silanized vials was found to be necessary to limit interaction of the basic tertiary amine component of VX with the acidic silanols present in standard glass vials. The polydimethylsiloxane (PDMS) fiber was ultimately selected for completion of this work with extractions being performed at 508C. Clothing material was spiked in the laboratory with 1 lL of neat VX, placed in a sealed vial, and taken into the field for SPME sampling, using optimized conditions studied. GC/MS analysis was also completed in the field using van-mounted instrumentation. With sampling and analysis completed in less than 20.0 minutes, detection of VX contamination was relatively rapid, especially considering the quality of the resulting data. The use of SPME also provides increased safety for the field analysis of VX since it does not require the handling of solvents for sample preparation and samples are not handled directly by the analyst.

Colorimetric Stimuli-Responsive Hydrogel Polymers for the Detection of Nerve Agent Surrogates

“…The mode of action for these nerve agents is the inhibition of the enzyme acetylcholinesterase, which results in continuous overstimulation of muscles that can ultimately result in death. The need for proper protection against these threats has led to the development of a variety of detection schemes for CWAs over the past few decades, 1,2 including chromatographic, [3][4][5][6] spectroscopic, 7-10 electrochemical, 11-15 fluorogenic, [16][17][18][19][20][21][22][23][24][25] and colorimetric [26][27][28][29] approaches. Fewer reports can be found for polymer-based detection schemes.…”

Methodological contributions towards LC–MS/MS quantification of free VX in plasma: An innovative approach

“…Initial optimizations were conducted in HBSS environment (receptor fluid of in vitro percutaneous penetration studies). Excellent yields (>99%) were achieved for a single extraction (v/v) and the protocol for (±) VX extraction was carried out as follows: 300 or 500 L of VX spiked HBSS (1 ng/mL) were placed in silanized vials [15] followed by the addition of 300 or 500 L (v/v) of diethyl ether (100%). Then, the tube was vortexed for 5 min and centrifuged at 1200 rpm for 5 min.…”

“…Stock solutions of VX (267 g/mL) and VR (5 mg/mL) were prepared in isopropanol. All solutions were stored and kept at −20 • C in silanized vials [15]. On the day of the experiment, additional dilutions were done for VR in HBSS to achieve a final concentration of 12.6 ng/mL.…”

“…The internal standard solution (8 L of a 12.6 ng/mL VR solution) was added to spiked plasma (1000 L) in silanized vials [15]. Then, 55 L of 1.00 M sodium hydroxide (NaOH) solution were added to the spiked plasma, vortexed for 5 s and fractionized into five vials to have approximately 200 L of solution in each vial.…”

“…Methodological adjustments. Since restricted plasma volumes were available, we had to introduce some adjustments regarding the (±) VX extraction protocol mainly by diluting 20 L of mouse plasma in 480 L of deionized water in silanized vials [15]. Then, it was added 8 L of internal standard solution followed by the addition of 8 L of 1.00 M sodium hydroxide (NaOH) and vortexed for 5 s. 500 L of diethyl ether/n-hexane (25/75, v/v) were added, vortexed for 10 min and centrifuged at 3200 rpm for 5 min.…”