Poly(dimethylsiloxane) microchip electrophoresis with contactless conductivity detection for measurement of chemical warfare agent degradation products

The applicability of a poly(dimethylsiloxane) (PDMS) microfluidic device with contactless conductivity detection for the determination of organophosphonate nerve agent degradation products is reported. Five alkyl methylphosphonic acids, isopropyl methylphosphonic acid (IMPA), pinacolyl methylphosphonic acid (PMPA), O-ethyl-N,N-dimethyl phosphoramidate (EDPA), ethyl methylphosphonic acid (EMPA), and methylphosphonic acid (MPA), (degradation products of Sarin, Soman, Tuban and VX nerve agents) were analyzed by microchip capillary electrophoresis. Experimental conditions for the separation and detection processes have been optimized to yield well-defined separation and high sensitivity. Under optimal conditions, analyses were completed in less than 2min. Linear relations between concentration and peak heights were obtained with detection limits in the 1.3-4.5mg/l range and precision values for the peak heights were in the range of 3.4-6.1% RSD. Applicability of this method for natural (lake and tap) water samples was also demonstrated. Compared to conventional analytical methods, this miniaturized system offers promise for on-site monitoring of degradation products of chemical warfare agents, with advantages of cost effective construction, simple operation, portability, and minimum sample consumption.