Detection of TATP precursors with MOX gas sensors combined with Solid Phase Micro Extraction

We present here a system for the detection of TATP precursors based on Headspace Solid Phase Micro Extraction (SPME) as sampling method and Tin Oxide gas sensors. The system includes a nitrogen bottle with a gas flowmeter connected to the injector of a gas chromatograph. The cell containing a tin dioxide multisensor was mounted inside the chromatograph oven connected to the injector, replacing the chromatographic column. The sensor response is measured using a Keithley K2700 with a 20-channel switch and connected trough GPIB interface to a computer. A program developed in Labview controls the system. The program displays and controls the measurement parameters and generates the response database. Multivariate analyses like Principal Component Analysis (PCA) and Artificial Neural Networks (ANN) have been applied to the data to discriminate among the different group of samples. The results show that both the precursors of TATP and the interferents measured are detected with the designed system.