Molluscan safety monitoring programs search for control systems able to give an estimation of the concentration levels of marine toxins present in water, which could represent a risk for the health of consumers of shellfish products. In this study a deployment of passive sampling devices consisting of resin filled sachets was carried out weekly during two years in Alfacs Bay, a coastal embayment of the Ebro Delta in the NW Mediterranean, Spain. Lipophilic marine toxin concentration profiles were obtained analyzing the content of the polymeric resins after extraction and analysis by liquid chromatography coupled to a quadrupole ion trap mass spectrometer.