Involved in atmospheric, biological and industrial processes, ammonia must be monitored and controlled in order to limit health impact for human and livestock or defects in industrial productions. Polyaniline (PAni) based chemiresistive sensors are promising for ammonia detection at ppb level whereas no commercial sensors are available for this purpose. Yet, the impact of potential interfering gas, chemically close to ammonia on the sensor response is not well studied. An increasing number of publications considers the impact of interfering species such as acetone or water while characterizing PAni based gas sensors. However, gases with physicochemical properties more comparable to ammonia’s properties might induce high sensor response from the PAni based sensor and are not so studied. The objective of this study is to investigate the impact of the PAni formulation on the sensor’s ability to discriminate ammonia from three selected amines: methylamine (MA), dimethylamine (DMA) and trimethylamine (TMA). To do so, different sensors based on emeraldine base dispersed in dichloroacetic acid (DCA) were realized. In addition to this polymer, some formulations included camphor sulfonic acid (CSA) as co-dopant and polyurethane (PU) as performance enhancer. All the PAni based sensors were exposed to different ammonia concentrations from 50 to 240 ppb and then at each one of the three selected amines separately. Resistivity and humidity were monitored during the experimentation. We observed that for all sensors, MA induced the highest sensor response, followed by DMA. Sensors response to TMA was equal or lower than the response to ammonia, depending on the formulation. Formulation only including PAni had poor response to all gases. Adding CSA increased sensors sensibility for all gases. Sensors including PU showed the best sensibility to all gases. Interestingly, formulation including PU showed the worst selectivity toward ammonia. Results are discussed in light of the physicochemical properties (e.g. proton affinity, steric hindrance, etc.) of the selected gases.