A sensitive quantitative screening of coumarin in 43 commercially available cinnamons and cinnamon-containing foods was developed via HPTLC. Complex samples like cinnamon, tea, breakfast cereals, milk rice, jam, cinnamon stars and buns were extracted with methanol only. Separation was performed on silica gel with a mixture of n-hexane, ethyl acetate and ammonia. The specific detection via derivatization with an ethanolic potassium hydroxide solution resulted in fluorescent coumarin zones, measured at 365/>400nm after stabilization. Limits of detection and quantification were 200 and 400pg/band, respectively. Over all different sample types, the contents ranged from 0.3 to 5129mg/kg with a mean repeatability and mean intermediate precision of 4% each. HPTLC-MS of selected zones, eluted via the TLC-MS Interface into MS, confirmed the identity of coumarin. Effect-directed detection as bioanalytical tool for risk assessment showed coumarin to be active against Aliivibrio fischeri bacteria down to 100ng/band.