Highly Selective Lead(II) Coated Graphite Sensor Based on 4,13-Didecyl-1,7,10,16-tetraoxa-4,13-diazacyclooctadecane as a Neutral Ionophore

摘要

4,13-Didecyl-1,7,10,16-tetraoxa-4,13-diazacyclooctadecane (kryptofix22DD) has been explored as a neutral ionophore for preparing polyvinyl chloride (PVC)-based membrane sensor selective to lead(II). The optimized membrane incorporating kryptofix22DD as the active material, nitrobenzene as plasticizer and sodium tetraphenylborate as an anion excluder and membrane modifier in PVC (in the weight ratio of 5.0: 63.0: 2.0: 30.0, respectively) was directly coated on the surface of graphite rod. The sensor exhibits a Nernstian slope (29.4 mV/decade) in the concentration range of 1.0 x 10(-5) to 1.0 x 10(-1) M Pb2+. The detection limit of the sensor is 6.5 x 10(-6) M. The proposed sensor has a fast response time (similar to 10 s), a satisfactory reproducibility and relatively long lifetime. The electrode shows high selectivity toward Pb2+ ion in comparison to other common cations. The proposed sensor is suitable for use in aqueous solutions in a wide pH range of 2.0-10.0. It was used as an indicator electrode for the end point detection in the potentiometric titration of Pb2+ ion with ethylenediaminetetraacetic acid (EDTA) and sodium iodide (NaI) solutions. The proposed sensor was successfully applied for the recovery of Pb2+ ions spiked in real water samples.