Sampling and analyses of surfaces contaminated with chemical warfare agents by using a newly developed triple layered composite wipe.

A three-layered composite wipe was fabricated by laminating individual layers of non-woven polypropylene, activated carbon fabric (ACF) and aramid fabric for the sampling and investigation of chemical warfare agents (CWA)-contaminated urban porous and non-porous surfaces. The material of main ACF layer was characterized to ascertain its suitability to act as an efficient adsorbent for the surface wipe sampling. The performance of ACF-based composite wipe was determined by evaluating its extraction efficiency, wiping efficacy and adsorption capacity for the sampling of blister and nerve agent class of CWA-contaminated surfaces using gas chromatography-mass spectrometry (GC-MS). Parameters like amount of wipe required, solvent selection, amount of solvent, time of extraction etc. were optimized to achieve the maximum recovery of contaminating analytes required for the forensic investigations. Overall recoveries of contaminating analytes after sampling and extraction were found to be in the range of 45-85% for all types of surfaces. No breakthrough in wiping process was noticed up to contamination density (CD) 1.6 mg/cm2 for non-porous surface and 3.2 mg/cm2 for porous surfaces. ACF-based wipe was found capable to significantly reduce the vapour hazards from liquid sulphur mustard (HD) and sarin (GB). Contamination from surfaces could be preserved within the wipe up to 15 days for the extended forensic investigation purposes. Limit of detections (LOD) of contaminants was determined in the range of 0.8-6.8 ng/cm2 while limit of quantitation (LOQ) was achieved up to the range of 2.4-14.4 ng/cm2 for wipe sampling of different surfaces. Graphical abstract.