The monitoring of marine dinophysistoxin okadaic acid in seawater can serve as an early alert system for preventing the potential negative effects this toxin can have on the food industry and human health in general. A disposable sensor system for electrochemical detection of this toxin has been developed using screen-printed electrodes. The method described is based on the inhibition of protein phosphatase type 2A by okadaic acid, evaluating the enzyme activity. p-Nitrophenyl phosphate, 4-methylumbelliferyl phosphate and phenyl phosphate have been tested as substrates achieving good limits of detection of 2.7·10–12 M of okadaic acid. The proposed method has been successfully applied to okadaic acid determination in seawater samples. A study of divalent cations present in seawater that can interfere with the measurement has been carried out. The electrode systems were printed on both rigid and textile backing materials to observe the influence of those materials on the final performance of the sensor.
