The increment of uncontrolled nutrients concentration in water is the subject of increasing environmental concern. In particular, the increment of nitrate causes the eutrophication of algae, leading to fauna and flora demise.[1] In order to favour an easy and adequate monitoring of this environmental problem, we have developed an ionogel-based sensor for the colorimetric determination and image analysis detection of nitrite and nitrate in water. The sensor consists on a small poly(methyl)methacrilate (PMMA) device cut by a CO2 laser where both the detection and the calibration zones are integrated. A simple photograph of the whole device, followed by colour processing of the different sections of the chip was used for the determination of nitrite concentrations.