Ammonia is a well-known pollutant that is emitted in large quantities in the agriculture industry, largely from animal rearing. In this work, we present a new optoelectronic nose based on Mach-Zehnder interferometry using silicon technology and peptides as the sensing method. The purpose of this paper is to characterize the performance of the functionalized silicon photonics sensor by using a reference instrument based on UV spectrophotometry, provided by HEMERA. The instrument set-up used enabled a serial sampling methodology using the two devices. The gas sample was analyzed simultaneously by the optoelectronic nose and the spectrophotometer device at the same flow rate. Different concentrations of ammonia samples diluted in water were prepared and measured with this set-up. A collection of samples at different ammonia concentrations was acquired and analyzed. The results highlighted a high sensitivity (sub-ppmv) of the optoelectronic nose with respect to the ammonia concentration. The optoelectronic nose provides benefits for ammonia measurement since i/ it can be a complementary instrument to UV spectrophotometry for which common interferences are not the same ii/ it is more cost effective and compact compared to alternate reference accurate techniques iii/ it provides real-time results.