A novel device has been developed that is capable of measuring anti-oxidant activity with a cost-efficient measurement method, in-line with HPLC. The device is based on a microfluidic chip that mixes the HPLC eluent stream with an antioxidant marker and integrates the analysis by conventional UV/VIS photonic sensors. The results enable assessment of the compounds responsible for the antioxidant capacity of analyzed food sample. This knowledge helps to select the most promising marker compounds for tracing antioxidant capacity changes from farm to fork through the food chain.