PVC Membrane Potentiometric Sensor Based on a Schiff Base for Determination of Ho3+ ions

Due to the importance of selective determination of the rare earth elements, construction of a novel holmium PVC membrane sensor based on 3-[(pyridine-2- ylmethylene)-amino]-2-thioxo-4-one (PMAT) as a neutral carrier, (DBP) as a plasticizer and (KTpClPB) as anionic additive is reported. The sensor has a Nernstian slope of 21.0±0.4 mV per decade and a linear dynamic range between 1.0×10-6 and 1.0×10-2 mol L-1. The mentioned sensor can be used in pH range of 4-7.5 and has a detection limit of 7.0×10-7 mol L-1. It has at least 4 weeks applicability life time, possesses the advantages of fast response time, and very good selectivity over a large number of cations, especially for lanthanide ions. The sensor was used as an indicator electrode in the potentiometric titration of fluoride ions of mouthwash with 1.0×10-3 mol L-1 solution of Ho3+ ion.