BACKGROUNDThis work proposes an optical fiber sensor to monitor the presence of volatile organic compounds (VOCs). The sensor consists of a single-mode fiber 1 cm long, coated with a composite of Prussian blue and an acrylic polymeric emulsion, inserted between two multimode fibers. RESULTSThe presence of VOCs modifies the optical properties of the composite layer and produces attenuation changes of the evanescent field. These attenuation changes can be easily monitored by a simple experimental set-up. The fabrication of the sensor is very simple which makes this sensor very attractive. The fabricated sensor was tested with three different VOC gases, acetone, isopropyl alcohol and chloroform. The response of the sensor was different for each gas, but in all cases the regression analysis was linear. CONCLUSIONIt was demonstrated that this VOC sensor can be used to detect volatile hydrocarbons, generated or forced to migrate from the solid phase (soil) to the gas phase (air) during the application of electrokinetic treatment to the polluted soil or in the environment. (c) 2016 Society of Chemical Industry