Volatile organic compounds (VOCs) include a wide range of molecules (e.g., carboxylic acids, terpenes, alcohols, etc.) characterized by a low boiling point. Most of them are released by plants in response to biotic and abiotic stresses as a defense system from pathogens and in promoting growth and crops (e.g., photosynthesis, nutrient metabolism). VOC analysis can be a useful tool for retrieving health status information, promoting sustainable agriculture. Hereafter, the development of a VOC sensor, for the monitoring of VOCs emitted by plants is presented. To improve the selectivity of commercial detector, a nanoporous adsorbing layer of zeolite layer was combined with commercial photoionization device (PID). VOC emission analysis was conducted on samples of propionic and succinic acids at different concentration using by a temperature-controlled desorption process. VOCs are detected and quantified by evaluating emission profiles considering an evaporation/diffusion model. Results showed that the proposed approach can improve the selective of a commercial PID taking advantage of short time analysis and low volumes liquid samples.