(25d) Highly Sensitive Multiphase Micro-Sensor as Micro-Gas Chromatography Detector for Selective Detection of Toxic Phosphonates

The objective of this paper is to report optimization and integration of a multiphase MEMS- based phosphonate sensor that utilizes selective, liquid chemistry in order to detect toxic phosphonate compounds eluting from a microfabricated gas chromatography (ì-GC) column. Previous work from our laboratory demonstrated that phosphonate molecules can be detected with such a device, but the sensitivity was insufficient for certain applications (e.g. detection of pesticides in foodstuffs) and the response time of the detector is too long for the desired separation with a ì-GC column.

In this paper temperature and injector assembly pressure were optimized and the selectivity of the sensor was tested with interferent mixtures. We find that i) the current sensor design is more sensitive and more selective than previously developed detection methods, ii) the peak width of the optimized sensor makes it a viable ì-GC sensor, and iii) the sensor can detect target molecules from complex mixtures that non-selective detection methods cannot distinguish due to peak overlap. The optimized device can selectively detect 109 molecules of acetylcholinesterase inhibitors (most notably toxic phosphonates) with a minimum peak width of 0.2 seconds.