Development of VOCs Sensor Based on Synthetic Zeolite Layers

Abstract

AbstractEndogenous or exogenous process byproducts include a wide range of chemicals, which can be used as promising candidate biomarkers for systemic diseases. Among them, Volatile Organic Compounds (VOCs) expressed in biological fluids could be evaluated through non-invasive techniques for the diagnosis and follow-up of a pathological condition (e.g., inflammatory process, neoplasia, etc.). Among VOCs contained in biological fluids, propionic and succinic acids are involved in important inflammatory processes. The development of a reliable, non-invasive sensor for the rapid quantification of VOCs is thus a topic of interest, especially for the screening of large populations. To this end, we investigated synthetic zeolite as a nanoporous adsorbing layer for the development of a VOCs sensor. Zeolite type 4A has been used as it provides a large surface/area ratio, a well-defined porosity, and considerable ion-exchange capabilities. A detection system based on a photoionization system has been investigated. The quantification of VOCs was evaluated by analyzing the emission profiles during the desorption process, which is strongly influenced by the environmental parameters such as temperature. Results evidenced that the joint use of a zeolite layer and a photoionization system is able to detect and quantify the presence of propionic acid respect to the succinic, since the latter is poorly physically adsorbed in the layer. The overall device is thus able to detect and quantify specific VOCs trapped inside the zeolite layer with a linear relation between the desorbed molecules and the sample concentration.KeywordsZeoliteAdsorption processNanoporous materialsSensor application