Phthalocyanines as sensitive coatings for QCM sensors operating in liquids for the detection of organic compounds

Over the past decades there has been a remarkable progress in the development and application of the quartz crystal microbalance (QCM) in sensing devices for the detection and quantification of various molecules in gaseous environments. However, the reported use of QCM based chemical sensors in liquid media is still rather limited despite of some promising results already obtained. In this work, QCM sensors with phthalocyanines (Pcs) as sensitive materials are proposed as chemical sensors for the detection of low ppm levels of organic compounds in water. Detailed studies of such Pc based sensor operating in liquids are presented. QCM sensors coated with different nickel phthalocyanines having polyoxy and alkyloxy substituents are characterized in their liquid sensing properties. Several Pcs have been found very sensitive to a variety of organic solvents, which are also potential pollutants of water, with detection limits in the lower ppm range. Sensitivities and detections limits are given for eight organic compounds. Sensors are working fully reversible and reliable over long periods of time. The results of the sensor test experiments show that phthalocyanines are powerful sensing layers capable of working also in the liquid phase.