Explosives Detection in Sea Water with Phthalocyanine Quartz Crystal Microbalance Sensors

Quartz crystal microbalance (QCM) based chemical sensor systems are of high interest as an analysis method for direct chemical pollution assessment of natural waters or effluents from polluted sites. In this work, QCM sensors with selected phthalocyanines (Pcs) as sensitive materials are proposed for the direct detection and classification of explosives such as 2,4,6-trinitrotoluene (TNT) and 1,3,5-trinitro-1,3,5-triazinane (RDX) contained in aqueous samples. The sensors are found to be very sensitive especially to TNT having sensitivities as high as 100 Hz/ppm and detection limits in the low parts-per-billion range for this explosive. The results were verified with sea water samples. The sensors maintain their excellent sensing properties and are capable of reliable quantification down to low parts-per-million levels. Finally, the variations in the sensing properties among the Pcs, differing mainly in their metal centers, are explored using principal component analysis in regard to the classification capabilities of a sensor array.