Pesticides play a key role in the high yields achieved in modern agricultural food production. Besides their positive effect on increasing productivity they are intentionally toxic, often towards non-target organisms and contaminated food products can have a serious impact on human and environmental health. This paper demonstrates the potential of a gold nanoparticle-based microfluidic sensor for in field detection of dithiocarbamate pesticides at remote locations. Combining the attractive optical properties of gold nanoparticles with on chip mixing and detection, using a simple digital camera, a detection limit of 16 μg L-1 for Ziram, a dithiocarbamate pesticide, was obtained.