An optoelectronic flow-through detector for active ingredients determination in pharmaceutical formulations is explained. Two consecutive compact photodetector’s devices operating according to light-emitting diodes-solar cells concept where the LEDs acting as a light source and solar cells for measuring the attenuated light of the incident light at 180˚ have been developed. The turbidimetric detector, fabricated of ten light-emitting diodes and five solar cells only, integrated with a glass flow cell has been easily adapted in flow injection analysis manifold system. For active ingredients determination, the developed detector was successfully utilized for the development and validation of an analytical method for warfarin determination in pure and pharmaceutical preparations. The developed method is based on the forming of a white, turbid product as a result of a reaction between the warfarin and semicarbazide which was used as an oxidizing agent. The developed flow-through detector system is semi mechanized, economic in materials consumption, easy to operate and characterized by excellent analytical results. Both developed analytical devices used in two channels flow injection system allow for turbidimetric measurements of warfarin in 0.9–154 μg ml−1 and 123–1600 μg ml−1 ranges of concentration, with limits of detections 0.73 μg ml−1 and 24.66 μg ml−1 for photodetectors 1& 2 respectively. The turbidity measurement procedure for the current flow system offers to conduct 60 tests per hour of the warfarin which is the most needs of quality control analysis in industrial applications. To ensure the analytical usefulness of the flow system, the warfarin has been analyzed in the real samples with a fully acceptable agreement and a correlation between the results offered by the developed flow system and the official method.