Pesticide sensing in water with phthalocyanine based QCM sensors

Pesticide pollution in natural waters as a result of intensive agriculture and horticulture has a negative impact on humans and nature. New, cost effective analytical methods are under intense development for continuous monitoring of natural waters and on-field sample screening to meet future analysis needs. In this work the use of chemical sensor array technology based on phthalocyanine coated quartz crystal microbalance sensors is evaluated for direct pesticide analysis in aqueous samples for the first time. For this purpose the phthalocyanine core structure was chemically modified to increase sensor sensitivity and create sensors with widely diverging analyte responses. The obtained sensors show high sensitivities and pesticides detection limits down to 0.03 mg l−1 for common organophosphorus and organonitrogen pesticides such as fenthion and methiocarb. An array composed of selected sensors coated with materials having high variations in their sorption properties is shown to have substantial discrimination capabilities for the identification of various pesticides dissolved in water. Thus, QCM based sensor arrays are considered a promising platform for the direct analysis of aqueous samples.