Agriculture is Irelands largest indigenous sector underlining the need for simple, portable and cost effective methods of environmental monitoring of such areas. This research demonstrates a new method for the in-situ analysis of glyphosate, a broad spectrum herbicide, in environmental water samples utilising a 3D printed centrifugal microfluidic disc with smartphone detection. As-synthesized citrate capped copper nanoparticles (cc-CuNPs) were utilised as a nanozyme to catalyse the oxidation of 3,3’,5,5’-tetramethylbenzidine (TMB) which generates a faded blue coloured solution in the presence of hydrogen peroxide (H2O2). Results indicated that glyphosate boosted the catalytic activity of the cc-CuNPs in this reaction by reducing nanoparticle aggregation, which in turn increased the surface area of the cc-CuNPs. This hypothesis was backed up by a difference in the polydispersity index (PDI) - 0.60 and 0.49 without and with glyphosate respectively - with dynamic light scattering (DLS) also indicating a much lower presence of larger cc-CuNP clusters within the sample while in the presence of glyphosate. The increased catalytic activity allowed for the reaction to take place at room temperature, avoiding the need for heating during the incubation step. This facilitated the portability of the assay and its integration into a 3D printed microfluidic disc. The microfluidic disc was designed to contain six microfluidic channels, allowing parallel analysis of six samples, and printed using Polyjet technology for the first time. The analysis took place entirely within the disc, with detection done through photographs taken with a standard smartphone camera and analysed by imageJ (free) software. The resulting limit of detection (LOD) was calculated to be 0.35 ppm, which falls below the EPA global guidance value of 0.7 ppm for the limit of glyphosate in water. Recovery values found in tap and lake water spiked samples were between 87 % and 127 %. Overall we have demonstrated the ability to detect glyphosate in real water samples through the increased catalytic activity of the as-prepared cc-CuNPs in the chromogenic reaction of TMB and H2O2 in combination with a centrifugal microfluidic disc and smartphone detection. This simple, portable and cost effective method further advances the field of environmental chemistry and suggests more potential analysis that may be performed on the same microfluidic disc.